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/cramfs/inode.c b/fs/cramfs/inode.c
index a2ee8f9..853480d 100644
--- a/fs/cramfs/inode.c
+++ b/fs/cramfs/inode.c
@@ -318,11 +318,9 @@
 	root = get_cramfs_inode(sb, &super.root, 0);
 	if (IS_ERR(root))
 		goto out;
-	sb->s_root = d_alloc_root(root);
-	if (!sb->s_root) {
-		iput(root);
+	sb->s_root = d_make_root(root);
+	if (!sb->s_root)
 		goto out;
-	}
 	return 0;
 out:
 	kfree(sbi);