arm64: allwinner: a64: add NMI (R_INTC) controller on A64

Allwinner A64 SoC features a R_INTC controller, which controls the NMI
line, and this interrupt line is usually connected to the AXP PMIC.

Add support for it.
Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
[wens@csie.org: Add fallback sun6i-a31-r-intc compatible]
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>

arch/arm64/boot/dts/allwinner/sun50i-a64.dtsi

@@ -487,6 +487,15 @@ rtc: rtc@1f00000 {
 				     <GIC_SPI 41 IRQ_TYPE_LEVEL_HIGH>;
 		};
 
+		r_intc: interrupt-controller@1f00c00 {
+			compatible = "allwinner,sun50i-a64-r-intc",
+				     "allwinner,sun6i-a31-r-intc";
+			interrupt-controller;
+			#interrupt-cells = <2>;
+			reg = <0x01f00c00 0x400>;
+			interrupts = <GIC_SPI 32 IRQ_TYPE_LEVEL_HIGH>;
+		};
+
 		r_ccu: clock@1f01400 {
 			compatible = "allwinner,sun50i-a64-r-ccu";
 			reg = <0x01f01400 0x100>;