f2fs: clean up w/ dotdot_name

[ Upstream commit ff6584ac ]

Just cleanup, no logic changes.

Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Stable-dep-of: 884ee6dc ("f2fs: get rid of online repaire on corrupted directory")
Signed-off-by: Sasha Levin <sashal@kernel.org>