Since littlefs is in active development, it's not a good idea to use its
source code files directly. So upgrade littlefs v2.2.1 by using the littlefs
tar.gz release package instead.
Change-Id: I16d9cf0b6bca700a54ca86ed11d7c8c7f27a898f
Signed-off-by: liuhaitao <liuhaitao@xiaomi.com>