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/ocfs2/super.c b/fs/ocfs2/super.c
index 2b1184f..337687c 100644
--- a/fs/ocfs2/super.c
+++ b/fs/ocfs2/super.c
@@ -1166,9 +1166,8 @@
 		goto read_super_error;
 	}
 
-	root = d_alloc_root(inode);
+	root = d_make_root(inode);
 	if (!root) {
-		iput(inode);
 		status = -ENOMEM;
 		mlog_errno(status);
 		goto read_super_error;