Fix the following gcc warning:
drivers/usb/gadget/udc/gr_udc.c:51:19: warning: â€˜driver_desc’ defined
but not used [-Wunused-const-variable=]
 static const char driver_desc[] = DRIVER_DESC;
                   ^~~~~~~~~~~
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Link: https://lore.kernel.org/r/20200417073137.39968-1-yanaijie@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
 #define        DRIVER_DESC     "Aeroflex Gaisler GRUSBDC USB Peripheral Controller"
 
 static const char driver_name[] = DRIVER_NAME;
-static const char driver_desc[] = DRIVER_DESC;
 
 #define gr_read32(x) (ioread32be((x)))
 #define gr_write32(x, v) (iowrite32be((v), (x)))