uwb: fix compiler warning on i1480_est_id_table

Annotate i1480_est_id_table as '__used' to fix following warning:

  CC      drivers/uwb/i1480/i1480-est.o
drivers/uwb/i1480/i1480-est.c:94: warning: ‘i1480_est_id_table’ defined but not used
Signed-off-by: Namhyung Kim <namhyung@gmail.com>
Cc: David Vrabel <david.vrabel@csr.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/uwb/i1480/i1480-est.c

@@ -91,7 +91,7 @@ MODULE_LICENSE("GPL");
  *
  * [so we are loaded when this kind device is connected]
  */
-static struct usb_device_id i1480_est_id_table[] = {
+static struct usb_device_id __used i1480_est_id_table[] = {
 	{ USB_DEVICE(0x8086, 0xdf3b), },
 	{ USB_DEVICE(0x8086, 0x0c3b), },
 	{ },