powerpc: dts: p2020: Define PMC node

Copy definition of PMC node from upstream Linux kernel P2020 dts files.

Signed-off-by: Pali Rohár <pali@kernel.org>
diff --git a/arch/powerpc/dts/p2020-post.dtsi b/arch/powerpc/dts/p2020-post.dtsi
index d281bed..0d0cd22 100644
--- a/arch/powerpc/dts/p2020-post.dtsi
+++ b/arch/powerpc/dts/p2020-post.dtsi
@@ -104,6 +104,11 @@
 		reg = <0xe0000 0x1000>;
 		fsl,has-rstcr;
 	};
+
+	pmc: power@e0070 {
+		compatible = "fsl,mpc8548-pmc";
+		reg = <0xe0070 0x20>;
+	};
 };
 
 /* PCIe controller base address 0x8000 */