Renamed config -> cfg

Note this includes both the lfs3_config -> lfs3_cfg structs as well as
the LFS3_CONFIG -> LFS3_CFG include define:

- LFS3_CONFIG -> LFS3_CFG
- struct lfs3_config -> struct lfs3_cfg
- struct lfs3_file_config -> struct lfs3_file_cfg
- struct lfs3_*bd_config -> struct lfs3_*bd_cfg
- cfg -> cfg

We were already using cfg as the variable name everywhere. The fact that
these names were different was an inconsistency that should be fixed
since we're committing to an API break.

LFS3_CFG is already out-of-date from upstream, and there's plans for a
config rework, but I figured I'd go ahead and change it as well to lower
the chances it gets overlooked.

---

Note this does _not_ affect LFS3_TAG_CONFIG. Having the on-disk vs
driver-level config take slightly different names is not a bad thing.

lfs3.h

@@ -337,21 +337,21 @@ enum lfs3_btype {
 
 
 // Configuration provided during initialization of the littlefs
-struct lfs3_config {
+struct lfs3_cfg {
     // Opaque user provided context that can be used to pass
     // information to the block device operations
     void *context;
 
     // Read a region in a block. Negative error codes are propagated
     // to the user.
-    int (*read)(const struct lfs3_config *c, lfs3_block_t block,
+    int (*read)(const struct lfs3_cfg *c, lfs3_block_t block,
             lfs3_off_t off, void *buffer, lfs3_size_t size);
 
     // Program a region in a block. The block must have previously
     // been erased. Negative error codes are propagated to the user.
     // May return LFS3_ERR_CORRUPT if the block should be considered bad.
     #ifndef LFS3_RDONLY
-    int (*prog)(const struct lfs3_config *c, lfs3_block_t block,
+    int (*prog)(const struct lfs3_cfg *c, lfs3_block_t block,
             lfs3_off_t off, const void *buffer, lfs3_size_t size);
     #endif
 
@@ -360,23 +360,23 @@ struct lfs3_config {
     // are propagated to the user.
     // May return LFS3_ERR_CORRUPT if the block should be considered bad.
     #ifndef LFS3_RDONLY
-    int (*erase)(const struct lfs3_config *c, lfs3_block_t block);
+    int (*erase)(const struct lfs3_cfg *c, lfs3_block_t block);
     #endif
 
     // Sync the state of the underlying block device. Negative error codes
     // are propagated to the user.
     #ifndef LFS3_RDONLY
-    int (*sync)(const struct lfs3_config *c);
+    int (*sync)(const struct lfs3_cfg *c);
     #endif
 
 #ifdef LFS3_THREADSAFE
     // Lock the underlying block device. Negative error codes
     // are propagated to the user.
-    int (*lock)(const struct lfs3_config *c);
+    int (*lock)(const struct lfs3_cfg *c);
 
     // Unlock the underlying block device. Negative error codes
     // are propagated to the user.
-    int (*unlock)(const struct lfs3_config *c);
+    int (*unlock)(const struct lfs3_cfg *c);
 #endif
 
     // Minimum size of a read in bytes. All read operations will be a
@@ -597,7 +597,7 @@ struct lfs3_attr {
 };
 
 // Optional configuration provided during lfs3_file_opencfg
-struct lfs3_file_config {
+struct lfs3_file_cfg {
     // Optional statically allocated file cache buffer. Must be cache_size.
     // By default lfs3_malloc is used to allocate this buffer.
     void *cache_buffer;
@@ -722,7 +722,7 @@ typedef struct lfs3_bshrub {
 typedef struct lfs3_file {
     // btree/bshrub stuff is in here
     lfs3_bshrub_t b;
-    const struct lfs3_file_config *cfg;
+    const struct lfs3_file_cfg *cfg;
 
     // current file position
     #ifndef LFS3_KVONLY
@@ -804,7 +804,7 @@ typedef struct lfs3_grm {
 
 // The littlefs filesystem type
 typedef struct lfs3 {
-    const struct lfs3_config *cfg;
+    const struct lfs3_cfg *cfg;
     uint32_t flags;
     lfs3_size_t block_count;
     lfs3_size_t name_limit;
@@ -901,7 +901,7 @@ typedef struct lfs3 {
 // Returns a negative error code on failure.
 #ifndef LFS3_RDONLY
 int lfs3_format(lfs3_t *lfs3, uint32_t flags,
-        const struct lfs3_config *cfg);
+        const struct lfs3_cfg *cfg);
 #endif
 
 // Mounts a littlefs
@@ -913,7 +913,7 @@ int lfs3_format(lfs3_t *lfs3, uint32_t flags,
 //
 // Returns a negative error code on failure.
 int lfs3_mount(lfs3_t *lfs3, uint32_t flags,
-        const struct lfs3_config *cfg);
+        const struct lfs3_cfg *cfg);
 
 // Unmounts a littlefs
 //
@@ -1023,7 +1023,7 @@ int lfs3_file_open(lfs3_t *lfs3, lfs3_file_t *file,
 #ifndef LFS3_KVONLY
 int lfs3_file_opencfg(lfs3_t *lfs3, lfs3_file_t *file,
         const char *path, uint32_t flags,
-        const struct lfs3_file_config *cfg);
+        const struct lfs3_file_cfg *cfg);
 #endif
 
 // Close a file