f2fs: fix to call f2fs_commit_super() correctly

This patch fixes the bug reported by Sashiko:

We should call f2fs_commit_super() instead of __f2fs_commit_super() in
sanity_check_area_boundary() to update chksum valud along w/
raw_super->segment_count.

Cc: stable@kernel.org
Fixes: d440c52d3151 ("f2fs: support superblock checksum")
Signed-off-by: Chao Yu <chao@kernel.org>