x86: Add alias for SPI node in the board dts

Since Intel ICH SPI driver has been converted to driver model, we need
add an alias for SPI node in the board dts files otherwise SPI flash
won't be detected due to 'invalid bus' error.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/x86/dts/minnowmax.dts b/arch/x86/dts/minnowmax.dts
index 8f34369..ecd4a89 100644
--- a/arch/x86/dts/minnowmax.dts
+++ b/arch/x86/dts/minnowmax.dts
@@ -15,6 +15,7 @@
 
 	aliases {
 		serial0 = &serial;
+		spi0 = "/spi";
 	};
 
 	config {
@@ -28,7 +29,7 @@
 	spi {
 		#address-cells = <1>;
 		#size-cells = <0>;
-		compatible = "intel,ich";
+		compatible = "intel,ich-spi";
 		spi-flash@0 {
 			reg = <0>;
 			compatible = "sst,25vf016b", "spi-flash";