f2fs: support 3.4

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

Conflicts:
	fs/f2fs/data.c
	fs/f2fs/f2fs.h
	fs/f2fs/inode.c
	fs/f2fs/shrinker.c
	fs/f2fs/super.c
Signed-off-by: Samuel Pascua <pascua.samuel.14@gmail.com>