isdn: mISDN: avmfritz: constify pci_device_id.

pci_device_id are not supposed to change at runtime. All functions
working with pci_device_id provided by <linux/pci.h> work with
const pci_device_id. So mark the non-const structs as const.

File size before:
   text	   data	    bss	    dec	    hex	filename
   9963	   1936	     16	  11915	   2e8b	isdn/hardware/mISDN/avmfritz.o

File size After adding 'const':
   text	   data	    bss	    dec	    hex	filename
  10091	   1808	     16	  11915	   2e8b	isdn/hardware/mISDN/avmfritz.o
Signed-off-by: NArvind Yadav <arvind.yadav.cs@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/isdn/hardware/mISDN/avmfritz.c

@@ -1142,7 +1142,7 @@ fritz_remove_pci(struct pci_dev *pdev)
 			pr_info("%s: drvdata already removed\n", __func__);
 }
 
-static struct pci_device_id fcpci_ids[] = {
+static const struct pci_device_id fcpci_ids[] = {
 	{ PCI_VENDOR_ID_AVM, PCI_DEVICE_ID_AVM_A1, PCI_ANY_ID, PCI_ANY_ID,
 	  0, 0, (unsigned long) "Fritz!Card PCI"},
 	{ PCI_VENDOR_ID_AVM, PCI_DEVICE_ID_AVM_A1_V2, PCI_ANY_ID, PCI_ANY_ID,