f2fs: jump to label 'free_node_inode' when failing from d_make_root()

When sb->s_root is NULL dput() will do nothing,
so jump to label 'free_node_inode' instead of lable
'free_root_inode' when failing from d_make_root().

Signed-off-by: Chengguang Xu <cgxu519@gmx.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>