extmod/vfs_fat: Remove unused function fat_vfs_listdir.

extmod/vfs_fat.h

@@ -59,5 +59,4 @@ mp_import_stat_t fat_vfs_import_stat(struct _fs_user_mount_t *vfs, const char *p
 mp_obj_t fatfs_builtin_open_self(mp_obj_t self_in, mp_obj_t path, mp_obj_t mode);
 MP_DECLARE_CONST_FUN_OBJ_KW(mp_builtin_open_obj);
 
-mp_obj_t fat_vfs_listdir(const char *path, bool is_str_type);
 mp_obj_t fat_vfs_listdir2(struct _fs_user_mount_t *vfs, const char *path, bool is_str_type);

extmod/vfs_fat_misc.c

@@ -36,10 +36,6 @@
 
 // TODO: actually, the core function should be ilistdir()
 
-mp_obj_t fat_vfs_listdir(const char *path, bool is_str_type) {
-    return fat_vfs_listdir2(NULL, path, is_str_type);
-}
-
 mp_obj_t fat_vfs_listdir2(fs_user_mount_t *vfs, const char *path, bool is_str_type) {
     FRESULT res;
     FILINFO fno;