usb: fsl: Check memory resource before releasing it

Check memory resource existence before releasing it to avoid NULL
pointer dereference
Signed-off-by: Nikhil Badola <nikhil.badola@freescale.com>
Reviewed-by: Ran Wang <ran.wang_1@nxp.com>
Reviewed-by: Peter Chen <peter.chen@nxp.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/gadget/udc/fsl_udc_core.c

@@ -2576,7 +2576,7 @@ static int fsl_udc_remove(struct platform_device *pdev)
 	dma_pool_destroy(udc_controller->td_pool);
 	free_irq(udc_controller->irq, udc_controller);
 	iounmap(dr_regs);
-	if (pdata->operating_mode == FSL_USB2_DR_DEVICE)
+	if (res && (pdata->operating_mode == FSL_USB2_DR_DEVICE))
 		release_mem_region(res->start, resource_size(res));
 
 	/* free udc --wait for the release() finished */