rtl8192cu: 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/realtek/rtlwifi/rtl8192cu/sw.c

@@ -279,7 +279,7 @@ static struct rtl_hal_cfg rtl92cu_hal_cfg = {
 #define USB_VENDER_ID_REALTEK		0x0bda
 
 /* 2010-10-19 DID_USB_V3.4 */
-static struct usb_device_id rtl8192c_usb_ids[] = {
+static const struct usb_device_id rtl8192c_usb_ids[] = {
 
 	/*=== Realtek demoboard ===*/
 	/* Default ID */