arm64: dts: r8a7796: Link ARM GIC to clock and clock domain

Link the ARM GIC to the INTC-AP module clock, and add it to the SYSC
"always-on" PM Domain, so it can be power managed using that clock.

Note that currently the GIC-400 driver doesn't support module clocks nor
Runtime PM, so this must be handled as a critical clock.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

arch/arm64/boot/dts/renesas/r8a7796.dtsi

@@ -101,6 +101,9 @@ gic: interrupt-controller@f1010000 {
 			      <0x0 0xf1060000 0 0x20000>;
 			interrupts = <GIC_PPI 9
 					(GIC_CPU_MASK_SIMPLE(1) | IRQ_TYPE_LEVEL_HIGH)>;
+			clocks = <&cpg CPG_MOD 408>;
+			clock-names = "clk";
+			power-domains = <&sysc R8A7796_PD_ALWAYS_ON>;
 		};
 
 		timer {