isdn: mISDN: hfcpci: 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
  21656	   1024	     96	  22776	   58f8	isdn/hardware/mISDN/hfcpci.o

File size After adding 'const':
   text	   data	    bss	    dec	    hex	filename
  22424	    256	     96	  22776	   58f8	isdn/hardware/mISDN/hfcpci.o
Signed-off-by: NArvind Yadav <arvind.yadav.cs@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/isdn/hardware/mISDN/hfcpci.c

@@ -2161,7 +2161,7 @@ static const struct _hfc_map hfc_map[] =
 	{},
 };
 
-static struct pci_device_id hfc_ids[] =
+static const struct pci_device_id hfc_ids[] =
 {
 	{ PCI_VDEVICE(CCD, PCI_DEVICE_ID_CCD_2BD0),
 	  (unsigned long) &hfc_map[0] },