HID: wacom: generic: support touch on/off softkey

Wacom Cintiq Pro has a softkey to turn touch on/off. Since it is
a softkey, hardware/firmware still reports touch events no matter
what state the softkey is. We need to ignore touch events when
the key is in off mode.

Signed-off-by: Ping Cheng <ping.cheng@wacom.com>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Tested-by: Aaron Armstrong Skomra <aaron.skomra@wacom.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/drivers/hid/wacom_wac.h b/drivers/hid/wacom_wac.h
index d9669c6..839bd4b 100644
--- a/drivers/hid/wacom_wac.h
+++ b/drivers/hid/wacom_wac.h
@@ -121,6 +121,7 @@
 #define WACOM_HID_WD_EXPRESSKEY00       (WACOM_HID_UP_WACOMDIGITIZER | 0x0910)
 #define WACOM_HID_WD_EXPRESSKEYCAP00    (WACOM_HID_UP_WACOMDIGITIZER | 0x0950)
 #define WACOM_HID_WD_MODE_CHANGE        (WACOM_HID_UP_WACOMDIGITIZER | 0x0980)
+#define WACOM_HID_WD_MUTE_DEVICE        (WACOM_HID_UP_WACOMDIGITIZER | 0x0981)
 #define WACOM_HID_WD_CONTROLPANEL       (WACOM_HID_UP_WACOMDIGITIZER | 0x0982)
 #define WACOM_HID_WD_ONSCREEN_KEYBOARD  (WACOM_HID_UP_WACOMDIGITIZER | 0x0983)
 #define WACOM_HID_WD_BUTTONCONFIG       (WACOM_HID_UP_WACOMDIGITIZER | 0x0986)
@@ -274,6 +275,7 @@ struct wacom_shared {
 	struct hid_device *pen;
 	struct hid_device *touch;
 	bool has_mute_touch_switch;
+	bool is_touch_on;
 };
 
 struct hid_data {