test: Add tests for SOC uclass

Add a sandbox SOC driver, and some tests for the SOC uclass.

Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
diff --git a/arch/sandbox/dts/test.dts b/arch/sandbox/dts/test.dts
index 3744a46..2ae4239 100644
--- a/arch/sandbox/dts/test.dts
+++ b/arch/sandbox/dts/test.dts
@@ -521,6 +521,10 @@
 		};
 	};
 
+	chipid: chipid {
+		compatible = "sandbox,soc";
+	};
+
 	i2s: i2s {
 		compatible = "sandbox,i2s";
 		#sound-dai-cells = <1>;