usb: fix integer as NULL pointer warnings found by sparse

drivers/usb/host/ohci-sm501.c:93:24: warning: Using plain integer as NULL pointer
drivers/usb/gadget/amd5536udc.c:3254:9: warning: Using plain integer as NULL pointer
drivers/usb/gadget/amd5536udc.c:3267:9: warning: Using plain integer as NULL pointer
drivers/usb/gadget/amd5536udc.c:3277:9: warning: Using plain integer as NULL pointer
drivers/usb/gadget/amd5536udc.c:3285:9: warning: Using plain integer as NULL pointer
drivers/usb/gadget/amd5536udc.c:3293:9: warning: Using plain integer as NULL pointer
Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/gadget/amd5536udc.c

@@ -3251,7 +3251,7 @@ static int udc_pci_probe(
 	/* pci setup */
 	if (pci_enable_device(pdev) < 0) {
 		kfree(dev);
-		dev = 0;
+		dev = NULL;
 		retval = -ENODEV;
 		goto finished;
 	}
@@ -3264,7 +3264,7 @@ static int udc_pci_probe(
 	if (!request_mem_region(resource, len, name)) {
 		dev_dbg(&pdev->dev, "pci device used already\n");
 		kfree(dev);
-		dev = 0;
+		dev = NULL;
 		retval = -EBUSY;
 		goto finished;
 	}
@@ -3274,7 +3274,7 @@ static int udc_pci_probe(
 	if (dev->virt_addr == NULL) {
 		dev_dbg(&pdev->dev, "start address cannot be mapped\n");
 		kfree(dev);
-		dev = 0;
+		dev = NULL;
 		retval = -EFAULT;
 		goto finished;
 	}
@@ -3282,7 +3282,7 @@ static int udc_pci_probe(
 	if (!pdev->irq) {
 		dev_err(&dev->pdev->dev, "irq not set\n");
 		kfree(dev);
-		dev = 0;
+		dev = NULL;
 		retval = -ENODEV;
 		goto finished;
 	}
@@ -3290,7 +3290,7 @@ static int udc_pci_probe(
 	if (request_irq(pdev->irq, udc_irq, IRQF_SHARED, name, dev) != 0) {
 		dev_dbg(&dev->pdev->dev, "request_irq(%d) fail\n", pdev->irq);
 		kfree(dev);
-		dev = 0;
+		dev = NULL;
 		retval = -EBUSY;
 		goto finished;
 	}

drivers/usb/host/ohci-sm501.c

@@ -90,7 +90,7 @@ static int ohci_hcd_sm501_drv_probe(struct platform_device *pdev)
 	struct device *dev = &pdev->dev;
 	struct resource	*res, *mem;
 	int retval, irq;
-	struct usb_hcd *hcd = 0;
+	struct usb_hcd *hcd = NULL;
 
 	irq = retval = platform_get_irq(pdev, 0);
 	if (retval < 0)