Adopted more conventional buffer parameter ordering

Adopted buffer followed by size. The other order was original
chosen due to some other functions with a more complicated
parameter list.

This convention is important, as the bd api is one of the main
apis facing porting efforts.

emubd/lfs_emubd.c

@@ -72,7 +72,7 @@ void lfs_emubd_destroy(const struct lfs_config *cfg) {
 }
 
 int lfs_emubd_read(const struct lfs_config *cfg, lfs_block_t block,
-        lfs_off_t off, lfs_size_t size, void *buffer) {
+        lfs_off_t off, void *buffer, lfs_size_t size) {
     lfs_emubd_t *emu = cfg->context;
     uint8_t *data = buffer;
 
@@ -114,7 +114,7 @@ int lfs_emubd_read(const struct lfs_config *cfg, lfs_block_t block,
 }
 
 int lfs_emubd_prog(const struct lfs_config *cfg, lfs_block_t block,
-        lfs_off_t off, lfs_size_t size, const void *buffer) {
+        lfs_off_t off, const void *buffer, lfs_size_t size) {
     lfs_emubd_t *emu = cfg->context;
     const uint8_t *data = buffer;