fs: Fix syntax errors in comments

Delete the redundant word 'not'.

Link: https://lore.kernel.org/r/20220605125509.14837-1-wangxiang@cdjrlc.com


Signed-off-by: Xiang wangx <wangxiang@cdjrlc.com>
Signed-off-by: Jan Kara <jack@suse.cz>