cmd: fs: Add command to list supported fs types

Added command "fstypes" to list supported/included filesystems.

Signed-off-by: Niel Fourie <lusus@denx.de>
Cc: Simon Glass <sjg@chromium.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
[trini: Limit to sandbox]
Signed-off-by: Tom Rini <trini@konsulko.com>

include/fs.h

@@ -259,4 +259,15 @@ int do_fs_uuid(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[],
  */
 int do_fs_type(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[]);
 
+/**
+ * do_fs_types - List supported filesystems.
+ *
+ * @cmdtp: Command information for fstypes
+ * @flag: Command flags (CMD_FLAG_...)
+ * @argc: Number of arguments
+ * @argv: List of arguments
+ * @return result (see enum command_ret_t)
+ */
+int do_fs_types(struct cmd_tbl *cmdtp, int flag, int argc, char * const argv[]);
+
 #endif /* _FS_H */