ARC: [plat-hsdk]: enable DW SPI controller

HSDK SoC has DW SPI controller. Enable it in preparation of
enabling on-board SPI peripherals.

Acked-by: Alexey Brodkin <abrodkin@synopsys.com>
Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

arch/arc/boot/dts/hsdk.dts

@@ -8,6 +8,7 @@
  */
 /dts-v1/;
 
+#include <dt-bindings/gpio/gpio.h>
 #include <dt-bindings/reset/snps,hsdk-reset.h>
 
 / {
@@ -252,6 +253,19 @@
 			dma-coherent;
 		};
 
+		spi0: spi@20000 {
+			compatible = "snps,dw-apb-ssi";
+			reg = <0x20000 0x100>;
+			#address-cells = <1>;
+			#size-cells = <0>;
+			interrupts = <16>;
+			num-cs = <2>;
+			reg-io-width = <4>;
+			clocks = <&input_clk>;
+			cs-gpios = <&creg_gpio 0 GPIO_ACTIVE_LOW>,
+				   <&creg_gpio 1 GPIO_ACTIVE_LOW>;
+		};
+
 		creg_gpio: gpio@14b0 {
 			compatible = "snps,creg-gpio-hsdk";
 			reg = <0x14b0 0x4>;