HID: hid-ntrig: Single touch mode tap

Add DOUBLETAP to events emitted when in single touch only mode.

Users with a single touch firmware report not seeing the DOUBLETAP events; this
is a side effect of dropping old mapping for confidence. The confidence mapping
may be fine for singletouch mode but causes problems in multitouch mode.
Signed-off-by: Rafi Rubin <rafi@seas.upenn.edu>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/hid-ntrig.c

@@ -165,6 +165,8 @@ static int ntrig_event (struct hid_device *hid, struct hid_field *field,
 			 * to emit a normal (X, Y) position
 			 */
 			if (!nd->reading_mt) {
+				input_report_key(input, BTN_TOOL_DOUBLETAP,
+						 (nd->confidence != 0));
 				input_event(input, EV_ABS, ABS_X, nd->x);
 				input_event(input, EV_ABS, ABS_Y, nd->y);
 			}