switch open-coded instances of d_make_root() to new helper

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index 0e4c5c0..baf40e3 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -1362,10 +1362,10 @@
 		error = EINVAL;
 		goto out_syncd_stop;
 	}
-	sb->s_root = d_alloc_root(root);
+	sb->s_root = d_make_root(root);
 	if (!sb->s_root) {
 		error = ENOMEM;
-		goto out_iput;
+		goto out_syncd_stop;
 	}
 
 	return 0;
@@ -1384,8 +1384,6 @@
  out:
 	return -error;
 
- out_iput:
-	iput(root);
  out_syncd_stop:
 	xfs_syncd_stop(mp);
  out_unmount: