net: Provide a function to get the current MAC address

The current implementation exposes the eth_device struct to code that
needs to access the MAC address.  Add a wrapper function for this to
abstract away the pointer for this operation.

Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

include/net.h

@@ -111,6 +111,14 @@ struct eth_device *eth_get_dev(void)
 {
 	return eth_current;
 }
+
+static inline unsigned char *eth_get_ethaddr(void)
+{
+	if (eth_current)
+		return eth_current->enetaddr;
+	return NULL;
+}
+
 extern struct eth_device *eth_get_dev_by_name(const char *devname);
 extern struct eth_device *eth_get_dev_by_index(int index); /* get dev @ index */
 extern int eth_get_dev_index(void);		/* get the device index */