media: saa7146: mxb: constify pci_device_id

pci_device_id are not supposed to change at runtime. All functions
working with pci_device_id provided by <media/drv-intf/saa7146.h>
and <linux/pci.h> work with const pci_device_id. So mark the non-const
structs as const.
Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

drivers/media/pci/saa7146/mxb.c

@@ -819,7 +819,7 @@ static struct saa7146_pci_extension_data mxb = {
 	.ext = &extension,
 };
 
-static struct pci_device_id pci_tbl[] = {
+static const struct pci_device_id pci_tbl[] = {
 	{
 		.vendor    = PCI_VENDOR_ID_PHILIPS,
 		.device	   = PCI_DEVICE_ID_PHILIPS_SAA7146,