net: eth-uclass: add function eth_start_udev()

Add a function to start a given network device, and update eth_init()
to use it.

Signed-off-by: Jerome Forissier <jerome.forissier@linaro.org>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
diff --git a/net/eth-uclass.c b/net/eth-uclass.c
index e34d7af..5555f82 100644
--- a/net/eth-uclass.c
+++ b/net/eth-uclass.c
@@ -284,6 +284,27 @@
 }
 U_BOOT_ENV_CALLBACK(ethaddr, on_ethaddr);
 
+int eth_start_udev(struct udevice *dev)
+{
+	struct eth_device_priv *priv = dev_get_uclass_priv(dev);
+	int ret;
+
+	if (priv->running)
+		return 0;
+
+	if (!device_active(dev))
+		return -EINVAL;
+
+	ret = eth_get_ops(dev)->start(dev);
+	if (ret < 0)
+		return ret;
+
+	priv->state = ETH_STATE_ACTIVE;
+	priv->running = true;
+
+	return 0;
+}
+
 int eth_init(void)
 {
 	struct udevice *current = NULL;
@@ -328,20 +349,11 @@
 		if (current) {
 			debug("Trying %s\n", current->name);
 
-			if (device_active(current)) {
-				ret = eth_get_ops(current)->start(current);
-				if (ret >= 0) {
-					struct eth_device_priv *priv =
-						dev_get_uclass_priv(current);
-
-					priv->state = ETH_STATE_ACTIVE;
-					priv->running = true;
-					ret = 0;
-					goto end;
-				}
-			} else {
+			ret = eth_start_udev(current);
+			if (ret < 0)
 				ret = eth_errno;
-			}
+			else
+				break;
 
 			debug("FAIL\n");
 		} else {