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

drivers/usb/gadget/udc/fsl_udc_core.c

@@ -53,7 +53,6 @@
 #define	DMA_ADDR_INVALID	(~(dma_addr_t)0)
 
 static const char driver_name[] = "fsl-usb2-udc";
-static const char driver_desc[] = DRIVER_DESC;
 
 static struct usb_dr_device __iomem *dr_regs;