btrfs-progs: Fix an extent buffer leak in qgroups check

Qgroup verify codes will read fs root to check if the subvolume exists.
But it forgot to free the extent buffer read out, only freeing the
memory.

Fix it by also freeing the extent buffers.

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>

qgroup-verify.c

@@ -761,7 +761,7 @@ static int load_quota_info(struct btrfs_fs_info *info)
 			tmproot = btrfs_read_fs_root_no_cache(info, &root_key);
 			if (tmproot && !IS_ERR(tmproot)) {
 				count->subvol_exists = 1;
-				free(tmproot);
+				btrfs_free_fs_root(tmproot);
 			}
 		}