arm64: dts: r8a7795: Add Cortex-A53 PMU node

Enable the performance monitor unit for the Cortex-A53 cores on the
R8A7795 SoC.

Extracted from a patch by Takeshi Kihara in the BSP.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

arch/arm64/boot/dts/renesas/r8a7795.dtsi

@@ -340,6 +340,18 @@ pmu_a57 {
 					     <&a57_3>;
 		};
 
+		pmu_a53 {
+			compatible = "arm,cortex-a53-pmu";
+			interrupts = <GIC_SPI 84 IRQ_TYPE_LEVEL_HIGH>,
+				     <GIC_SPI 85 IRQ_TYPE_LEVEL_HIGH>,
+				     <GIC_SPI 86 IRQ_TYPE_LEVEL_HIGH>,
+				     <GIC_SPI 87 IRQ_TYPE_LEVEL_HIGH>;
+			interrupt-affinity = <&a53_0>,
+					     <&a53_1>,
+					     <&a53_2>,
+					     <&a53_3>;
+		};
+
 		timer {
 			compatible = "arm,armv8-timer";
 			interrupts = <GIC_PPI 13