dm: x86: Add a northbridge uclass

Add a uclass for the northbridge / SDRAM controller found on some older
Intel chipsets.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/arch/x86/lib/northbridge-uclass.c b/arch/x86/lib/northbridge-uclass.c
new file mode 100644
index 0000000..64b6257
--- /dev/null
+++ b/arch/x86/lib/northbridge-uclass.c
@@ -0,0 +1,15 @@
+/*
+ * Copyright (c) 2015 Google, Inc
+ * Written by Simon Glass <sjg@chromium.org>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <dm/root.h>
+
+UCLASS_DRIVER(northbridge) = {
+	.id		= UCLASS_NORTHBRIDGE,
+	.name		= "northbridge",
+};