FROMGIT: f2fs: fix comment in sanity_check_raw_super()

Commit d7e9a903 ("f2fs: Support Block Size == Page Size") missed to
adjust comment in sanity_check_raw_super(), fix it.

Change-Id: I5899dd6ba346fb5ad114261e845f196388d88ab3
Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
(cherry picked from commit 5bf624c0
https://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs.git dev)