dts: arm: microchip: mec172x: Use consistent dts property names

Use consistent name for SPI HW block properties across Microchip
HW,  so applications using a device tree overlay work
transparently.

Signed-off-by: Jose Alberto Meza <jose.a.meza.arellano@intel.com>
diff --git a/dts/arm/microchip/mec172xnsz.dtsi b/dts/arm/microchip/mec172xnsz.dtsi
index 5269154..c16d9df 100644
--- a/dts/arm/microchip/mec172xnsz.dtsi
+++ b/dts/arm/microchip/mec172xnsz.dtsi
@@ -758,7 +758,7 @@
 			clock-frequency = <12000000>;
 			label = "SPI_0";
 			lines = <1>;
-			chip-select = <0>;
+			chip_select = <0>;
 			#address-cells = <1>;
 			#size-cells = <0>;
 			status = "disabled";