f2fs: remove rename and use rename2

Refer the following patch.

commit 7177a9c4b5
Author: Miklos Szeredi <mszeredi@suse.cz>
Date:   Wed Jul 23 15:15:30 2014 +0200

    fs: call rename2 if exists

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

fs/f2fs/namei.c

@@ -704,7 +704,6 @@ const struct inode_operations f2fs_dir_inode_operations = {
 	.mkdir		= f2fs_mkdir,
 	.rmdir		= f2fs_rmdir,
 	.mknod		= f2fs_mknod,
-	.rename		= f2fs_rename,
 	.rename2	= f2fs_rename2,
 	.tmpfile	= f2fs_tmpfile,
 	.getattr	= f2fs_getattr,