x86: ivybridge: Add a driver for the bd82x6x northbridge

Add a driver with an empty probe function where we can move init code in
follow-on patches.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/arch/x86/dts/chromebook_link.dts b/arch/x86/dts/chromebook_link.dts
index f2db844..e2c722d 100644
--- a/arch/x86/dts/chromebook_link.dts
+++ b/arch/x86/dts/chromebook_link.dts
@@ -166,6 +166,13 @@
 		ranges = <0x02000000 0x0 0xe0000000 0xe0000000 0 0x10000000
 			0x42000000 0x0 0xd0000000 0xd0000000 0 0x10000000
 			0x01000000 0x0 0x1000 0x1000 0 0xefff>;
+
+		northbridge@0,0 {
+			reg = <0x00000000 0 0 0 0>;
+			compatible = "intel,bd82x6x-northbridge";
+			u-boot,dm-pre-reloc;
+		};
+
 		sata {
 			compatible = "intel,pantherpoint-ahci";
 			intel,sata-mode = "ahci";