f2fs: support 3.4

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

Conflicts:
	fs/f2fs/acl.c
	fs/f2fs/acl.h
	fs/f2fs/data.c
	fs/f2fs/dir.c
	fs/f2fs/f2fs.h
	fs/f2fs/file.c
	fs/f2fs/gc.c
	fs/f2fs/gc.h
	fs/f2fs/inode.c
	fs/f2fs/namei.c
	fs/f2fs/node.c
	fs/f2fs/recovery.c
	fs/f2fs/segment.c
	fs/f2fs/super.c
	fs/f2fs/xattr.c
	fs/f2fs/xattr.h
	include/trace/events/f2fs.h