libertas: 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: Arvind Yadav <arvind.yadav.cs@gmail.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/marvell/libertas/if_usb.c

@@ -52,7 +52,7 @@ static const struct lbs_fw_table fw_table[] = {
 	{ MODEL_8682, "libertas/usb8682.bin", NULL }
 };
 
-static struct usb_device_id if_usb_table[] = {
+static const struct usb_device_id if_usb_table[] = {
 	/* Enter the device signature inside */
 	{ USB_DEVICE(0x1286, 0x2001), .driver_info = MODEL_8388 },
 	{ USB_DEVICE(0x05a3, 0x8388), .driver_info = MODEL_8388 },