net: usbnet: Remove unused driver_name variable

With GCC 6.3, we can get the following warning:

drivers/net/usb/usbnet.c:85:19: warning: 'driver_name' defined but not
used [-Wunused-const-variable=]
 static const char driver_name [] = "usbnet";
                   ^~~~~~~~~~~
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/usb/usbnet.c

@@ -82,8 +82,6 @@
 // randomly generated ethernet address
 static u8	node_id [ETH_ALEN];
 
-static const char driver_name [] = "usbnet";
-
 /* use ethtool to change the level for any given device */
 static int msg_level = -1;
 module_param (msg_level, int, 0);