sandbox: eth: Add network support to sandbox

Add basic network support to sandbox which includes a network driver.

Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/sandbox/dts/sandbox.dts b/arch/sandbox/dts/sandbox.dts
index 42a1f21..0df7b40 100644
--- a/arch/sandbox/dts/sandbox.dts
+++ b/arch/sandbox/dts/sandbox.dts
@@ -201,4 +201,8 @@
 		};
 	};
 
+	eth@10002000 {
+		compatible = "sandbox,eth";
+		reg = <0x10002000 0x1000>;
+	};
 };