ARM: dts: sunxi: Fix PMU compatible strings

"arm,cortex-a15-pmu" is not a valid fallback compatible string for an
Cortex-A7 PMU, so drop it.

Cc: Maxime Ripard <maxime.ripard@bootlin.com>
Cc: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: NRob Herring <robh@kernel.org>
Acked-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NMaxime Ripard <maxime.ripard@bootlin.com>

arch/arm/boot/dts/sun6i-a31.dtsi

@@ -200,7 +200,7 @@
 	};
 
 	pmu {
-		compatible = "arm,cortex-a7-pmu", "arm,cortex-a15-pmu";
+		compatible = "arm,cortex-a7-pmu";
 		interrupts = <GIC_SPI 120 IRQ_TYPE_LEVEL_HIGH>,
 			     <GIC_SPI 121 IRQ_TYPE_LEVEL_HIGH>,
 			     <GIC_SPI 122 IRQ_TYPE_LEVEL_HIGH>,

arch/arm/boot/dts/sun7i-a20.dtsi

@@ -195,7 +195,7 @@
 	};
 
 	pmu {
-		compatible = "arm,cortex-a7-pmu", "arm,cortex-a15-pmu";
+		compatible = "arm,cortex-a7-pmu";
 		interrupts = <GIC_SPI 120 IRQ_TYPE_LEVEL_HIGH>,
 			     <GIC_SPI 121 IRQ_TYPE_LEVEL_HIGH>;
 	};