net: irda: stir4200: constify usb_device_id

usb_device_id are not supposed to change at runtime. All functions
working with usb_device_id provided by <linux/usb.h> work with
const usb_device_id. So mark the non-const structs as const.
Signed-off-by: NArvind Yadav <arvind.yadav.cs@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/irda/stir4200.c

@@ -183,7 +183,7 @@ struct stir_cb {
 
 
 /* These are the currently known USB ids */
-static struct usb_device_id dongles[] = {
+static const struct usb_device_id dongles[] = {
     /* SigmaTel, Inc,  STIr4200 IrDA/USB Bridge */
     { USB_DEVICE(0x066f, 0x4200) },
     { }