dm: eth: Add support for aliases

Allow network devices to be referred to as "eth0" instead of
"eth@12345678" when specified in ethact.

Add tests to verify this behavior.

Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/include/configs/sandbox.h b/include/configs/sandbox.h
index e225ce6..9769a8d 100644
--- a/include/configs/sandbox.h
+++ b/include/configs/sandbox.h
@@ -178,7 +178,7 @@
 
 #define SANDBOX_ETH_SETTINGS		"ethaddr=00:00:11:22:33:44\0" \
 					"eth1addr=00:00:11:22:33:45\0" \
-					"eth2addr=00:00:11:22:33:46\0" \
+					"eth5addr=00:00:11:22:33:46\0" \
 					"ipaddr=1.2.3.4\0"
 
 #define CONFIG_EXTRA_ENV_SETTINGS	SANDBOX_SERIAL_SETTINGS \
diff --git a/include/net.h b/include/net.h
index 0a1b3a8..942fa4c 100644
--- a/include/net.h
+++ b/include/net.h
@@ -124,6 +124,11 @@
 #define eth_get_ops(dev) ((struct eth_ops *)(dev)->driver->ops)
 
 struct udevice *eth_get_dev(void); /* get the current device */
+/*
+ * The devname can be either an exact name given by the driver or device tree
+ * or it can be an alias of the form "eth%d"
+ */
+struct udevice *eth_get_dev_by_name(const char *devname);
 unsigned char *eth_get_ethaddr(void); /* get the current device MAC */
 /* Used only when NetConsole is enabled */
 int eth_init_state_only(void); /* Set active state */