dts: x86: intel: alder_lake: Add second core

Alder Lake have at least 2 cores. Both boards using this SoC
(up_squared_pro_7000 and adl) are configured with
MP_MAX_NUM_CPUS=2, so dts should contain at least one more core.

Signed-off-by: Franciszek Pindel <fpindel@antmicro.com>

dts/x86/intel/alder_lake.dtsi

@@ -23,6 +23,13 @@
 			reg = <0>;
 		};
 
+		cpu@1 {
+			device_type = "cpu";
+			compatible = "intel,alder-lake";
+			d-cache-line-size = <64>;
+			reg = <1>;
+		};
+
 	};
 
 	dram0: memory@0 {