riscv: dts: Add DT support for SiFive FU540 GPIO driver

Add the gpio DT node in SiFive FU540 soc-specific DT file.
Enable the gpio node in HiFive Unleashed board-specific DT file.
Signed-off-by: NYash Shah <yash.shah@sifive.com>
Signed-off-by: NPalmer Dabbelt <palmerdabbelt@google.com>

arch/riscv/boot/dts/sifive/fu540-c000.dtsi

@@ -268,6 +268,19 @@
 			interrupts = <1 2 3>;
 			reg = <0x0 0x2010000 0x0 0x1000>;
 		};
-
+		gpio: gpio@10060000 {
+			compatible = "sifive,fu540-c000-gpio", "sifive,gpio0";
+			interrupt-parent = <&plic0>;
+			interrupts = <7>, <8>, <9>, <10>, <11>, <12>, <13>,
+				     <14>, <15>, <16>, <17>, <18>, <19>, <20>,
+				     <21>, <22>;
+			reg = <0x0 0x10060000 0x0 0x1000>;
+			gpio-controller;
+			#gpio-cells = <2>;
+			interrupt-controller;
+			#interrupt-cells = <2>;
+			clocks = <&prci PRCI_CLK_TLCLK>;
+			status = "disabled";
+		};
 	};
 };

arch/riscv/boot/dts/sifive/hifive-unleashed-a00.dts

@@ -94,3 +94,7 @@
 &pwm1 {
 	status = "okay";
 };
+
+&gpio {
+	status = "okay";
+};