powerpc: dts: p2020: Define L2 cache node

Copy definition of L2 cache node from upstream Linux kernel P2020 dts files.

Signed-off-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Priyanka Jain <priyanka.jain@nxp.com>
diff --git a/arch/powerpc/dts/p2020.dtsi b/arch/powerpc/dts/p2020.dtsi
index 7c4c206..7fdcb85 100644
--- a/arch/powerpc/dts/p2020.dtsi
+++ b/arch/powerpc/dts/p2020.dtsi
@@ -22,10 +22,12 @@
 		cpu0: PowerPC,P2020@0 {
 			device_type = "cpu";
 			reg = <0>;
+			next-level-cache = <&L2>;
 		};
 		cpu1: PowerPC,P2020@1 {
 			device_type = "cpu";
 			reg = <1>;
+			next-level-cache = <&L2>;
 		};
 	};
 };