media: serial_ir: use the right type for a dma address

As warned by smatch:
	drivers/media/rc/serial_ir.c:550 serial_ir_probe() warn: should '8 << ioshift' be a 64 bit type?

the "8" constant should be unsigned long.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

drivers/media/rc/serial_ir.c

@@ -547,7 +547,7 @@ static int serial_ir_probe(struct platform_device *dev)
 
 	/* Reserve io region. */
 	if ((iommap &&
-	     (devm_request_mem_region(&dev->dev, iommap, 8 << ioshift,
+	     (devm_request_mem_region(&dev->dev, iommap, 8UL << ioshift,
 				      KBUILD_MODNAME) == NULL)) ||
 	     (!iommap && (devm_request_region(&dev->dev, io, 8,
 			  KBUILD_MODNAME) == NULL))) {