btrfs: merge two superblock writing helpers

write_all_supers and write_ctree_super are almost equal, the parameter
'trans' is unused so we can drop it and have just one helper.

Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 5eefd77..c27f222 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -2257,7 +2257,7 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans)
 		goto scrub_continue;
 	}
 
-	ret = write_ctree_super(trans, fs_info, 0);
+	ret = write_all_supers(fs_info, 0);
 	if (ret) {
 		mutex_unlock(&fs_info->tree_log_mutex);
 		goto scrub_continue;