p54: 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: NKalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/intersil/p54/p54usb.c

@@ -41,7 +41,7 @@ MODULE_FIRMWARE("isl3887usb");
  * whenever you add a new device.
  */
 
-static struct usb_device_id p54u_table[] = {
+static const struct usb_device_id p54u_table[] = {
 	/* Version 1 devices (pci chip + net2280) */
 	{USB_DEVICE(0x0411, 0x0050)},	/* Buffalo WLI2-USB2-G54 */
 	{USB_DEVICE(0x045e, 0x00c2)},	/* Microsoft MN-710 */