[axge] Reapply USB device configuration when opening network device

When connected to a USB3 port, the AX88179 seems to have an
approximately 50% chance of producing a USB transaction error on each
of its three endpoints after being closed and reopened.  The root
cause is unclear, but rewriting the USB device configuration value
seems to clear whatever internal error state has accumulated.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/drivers/net/axge.h

@@ -145,6 +145,8 @@ struct axge_device {
 	struct net_device *netdev;
 	/** USB network device */
 	struct usbnet_device usbnet;
+	/** Device configuration */
+	unsigned int config;
 	/** Link state has changed */
 	int check_link;
 };