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/hppfs/hppfs.c b/fs/hppfs/hppfs.c
index d92f4ce..a80e45a 100644
--- a/fs/hppfs/hppfs.c
+++ b/fs/hppfs/hppfs.c
@@ -726,17 +726,12 @@
 
 	err = -ENOMEM;
 	root_inode = get_inode(sb, dget(proc_mnt->mnt_root));
-	if (!root_inode)
-		goto out_mntput;
-
-	sb->s_root = d_alloc_root(root_inode);
+	sb->s_root = d_make_root(root_inode);
 	if (!sb->s_root)
-		goto out_iput;
+		goto out_mntput;
 
 	return 0;
 
- out_iput:
-	iput(root_inode);
  out_mntput:
 	mntput(proc_mnt);
  out: