f2fs: fix time update in case of f2fs fallocate

After doing a punch hole or expanding inode doing fallocation.
The change and modification time are not update for the file.
So, update time after no issue is observed in fallocate.

Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Amit Sahrawat <a.sahrawat@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>