f2fs: enable inline dir handling

Add inline dir functions into normal dir ops' function to handle inline ops.
Besides, we enable inline dir mode when a new dir inode is created if
inline_data option is on.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

diff --cc fs/f2fs/dir.c
Simple merge

diff --cc fs/f2fs/file.c
Simple merge

diff --cc fs/f2fs/inline.c
Simple merge

diff --cc fs/f2fs/namei.c
Simple merge

diff --cc fs/f2fs/recovery.c
Simple merge