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/hpfs/super.c b/fs/hpfs/super.c
index 3690467c9..54f6ecc 100644
--- a/fs/hpfs/super.c
+++ b/fs/hpfs/super.c
@@ -625,11 +625,9 @@
 	hpfs_init_inode(root);
 	hpfs_read_inode(root);
 	unlock_new_inode(root);
-	s->s_root = d_alloc_root(root);
-	if (!s->s_root) {
-		iput(root);
+	s->s_root = d_make_root(root);
+	if (!s->s_root)
 		goto bail0;
-	}
 
 	/*
 	 * find the root directory's . pointer & finish filling in the inode