f2fs: fix typos in comments

[ Upstream commit 146949de ]

This patch is to fix typos in f2fs files.

Signed-off-by: Jinyoung Choi <j-young.choi@samsung.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Stable-dep-of: 278a6253 ("f2fs: fix to relocate check condition in f2fs_fallocate()")
Signed-off-by: Sasha Levin <sashal@kernel.org>