HID: input: add mapping for Expose/Overview key

According to HUTRR77 usage 0x29f from the consumer page is reserved for
the Desktop application to present all running user’s application windows.
Linux defines KEY_SCALE to request Compiz Scale (Expose) mode, so let's
add the mapping.
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/hid/hid-input.c

@@ -1030,6 +1030,8 @@ static void hidinput_configure_usage(struct hid_input *hidinput, struct hid_fiel
 		case 0x2cb: map_key_clear(KEY_KBDINPUTASSIST_ACCEPT);	break;
 		case 0x2cc: map_key_clear(KEY_KBDINPUTASSIST_CANCEL);	break;
 
+		case 0x29f: map_key_clear(KEY_SCALE);		break;
+
 		default: map_key_clear(KEY_UNKNOWN);
 		}
 		break;