usb: gadget: remove unused shortname variable

The shortname variable isn't referenced anywhere in the code, so just
remove it.

Pointed out by a GCC 6.2 default warning option.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Marek Vasut <marex@denx.de>
Acked-by: Lukasz Majewski <l.majewski@samsung.com>

drivers/usb/gadget/ether.c

@@ -80,7 +80,6 @@ unsigned packet_received, packet_sent;
 /* Based on linux 2.6.27 version */
 #define DRIVER_VERSION		"May Day 2005"
 
-static const char shortname[] = "ether";
 static const char driver_desc[] = DRIVER_DESC;
 
 #define RX_EXTRA	20		/* guard against rx overflows */