net: irda: irda-usb: 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/irda-usb.c

@@ -72,7 +72,7 @@
 static int qos_mtt_bits = 0;
 
 /* These are the currently known IrDA USB dongles. Add new dongles here */
-static struct usb_device_id dongles[] = {
+static const struct usb_device_id dongles[] = {
 	/* ACTiSYS Corp.,  ACT-IR2000U FIR-USB Adapter */
 	{ USB_DEVICE(0x9c4, 0x011), .driver_info = IUC_SPEED_BUG | IUC_NO_WINDOW },
 	/* Look like ACTiSYS, Report : IBM Corp., IBM UltraPort IrDA */