nfc: virtual_ncidev: constify pointer to nfc_dev

virtual_ncidev_ioctl() does not modify struct nfc_dev, so local variable
can be a pointer to const.
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/nfc/virtual_ncidev.c

@@ -170,7 +170,7 @@ static int virtual_ncidev_close(struct inode *inode, struct file *file)
 static long virtual_ncidev_ioctl(struct file *flip, unsigned int cmd,
 				 unsigned long arg)
 {
-	struct nfc_dev *nfc_dev = ndev->nfc_dev;
+	const struct nfc_dev *nfc_dev = ndev->nfc_dev;
 	void __user *p = (void __user *)arg;
 
 	if (cmd != IOCTL_GET_NCIDEV_IDX)