usb: gadget: xilinx: fix devm_ioremap_resource() check

devm_ioremap_resource() returns IOMEM_ERR_PTR() and it never
returns NULL, fix the check to prevent access to invalid
virtual address.

Signed-off-by: Vladimir Zapolskiy <vz@mleia.com>
Reviewed-by: Sören Brinkmann <soren.brinkmann@xilinx.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/gadget/udc/udc-xilinx.c

@@ -2071,8 +2071,8 @@ static int xudc_probe(struct platform_device *pdev)
  /* Map the registers */
  res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  udc->addr = devm_ioremap_resource(&pdev->dev, res);
- if (!udc->addr)
- return -ENOMEM;
+ if (IS_ERR(udc->addr))
+ return PTR_ERR(udc->addr);
 
  irq = platform_get_irq(pdev, 0);
  if (irq < 0) {