HID: wacom: Simplify check for presence of single-finger touch

To determine if a touch is present in the single-touch case, we can
simply check if the BTN_TOUCH key is active or not. This will work for
both HID_GENERIC and other device types.
Signed-off-by: NJason Gerecke <jason.gerecke@wacom.com>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

drivers/hid/wacom_wac.c

@@ -1072,9 +1072,8 @@ static int wacom_wac_finger_count_touches(struct wacom_wac *wacom)
 	int count = 0;
 	int i;
 
-	/* non-HID_GENERIC single touch input doesn't call this routine */
-	if ((touch_max == 1) && (wacom->features.type == HID_GENERIC))
-		return wacom->hid_data.tipswitch &&
+	if (touch_max == 1)
+		return test_bit(BTN_TOUCH, input->key) &&
 		       !wacom->shared->stylus_in_proximity;
 
 	for (i = 0; i < input->mt->num_slots; i++) {