powerpc/85xx/p2020: Add fsl,mpc8548-pmc node

P2020 also contains Power Management Controller and their registers at
offset 0xe0070 compatible with mpc8548. So add PMC node into DTS include
file fsl/p2020si-post.dtsi

Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220506203621.26314-1-pali@kernel.org

arch/powerpc/boot/dts/fsl/p2020si-post.dtsi

@@ -198,4 +198,9 @@
 		reg = <0xe0000 0x1000>;
 		fsl,has-rstcr;
 	};
+
+	pmc: power@e0070 {
+		compatible = "fsl,mpc8548-pmc";
+		reg = <0xe0070 0x20>;
+	};
 };