usb: gadget: fsl: remove unused variable 'driver_desc'

drivers/usb/gadget/udc/fsl_udc_core.c:56:19:
 warning: 'driver_desc' defined but not used [-Wunused-const-variable=]

It is never used, so remove it.

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Reviewed-by: Peter Chen <peter.chen@nxp.com>
Link: https://lore.kernel.org/r/20200326071419.19240-1-yuehaibing@huawei.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>