staging: rtl8188eu: 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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtl8188eu/os_dep/usb_intf.c

@@ -32,7 +32,7 @@
 #define USB_VENDER_ID_REALTEK		0x0bda
 
 /* DID_USB_v916_20130116 */
-static struct usb_device_id rtw_usb_id_tbl[] = {
+static const struct usb_device_id rtw_usb_id_tbl[] = {
 	/*=== Realtek demoboard ===*/
 	{USB_DEVICE(USB_VENDER_ID_REALTEK, 0x8179)}, /* 8188EUS */
 	{USB_DEVICE(USB_VENDER_ID_REALTEK, 0x0179)}, /* 8188ETV */