test: Load mac address using misc device

This loads a mac address using a misc device using the nvmem interface.

Signed-off-by: Sean Anderson <sean.anderson@seco.com>
diff --git a/drivers/misc/misc_sandbox.c b/drivers/misc/misc_sandbox.c
index 0e4292f..31cde2d 100644
--- a/drivers/misc/misc_sandbox.c
+++ b/drivers/misc/misc_sandbox.c
@@ -112,8 +112,11 @@
 int misc_sandbox_probe(struct udevice *dev)
 {
 	struct misc_sandbox_priv *priv = dev_get_priv(dev);
+	/* For eth5 */
+	const u8 mac[] = { 0x02, 0x00, 0x11, 0x22, 0x33, 0x46 };
 
 	priv->enabled = true;
+	memcpy(&priv->mem[16], mac, sizeof(mac));
 
 	return 0;
 }