mfd: Add BTN_TOUCH event to ucb1x00-ts

Add BTN_TOUCH event reporting to ucb1x00_ts touchscreen driver.
This will make this touchscreen driver behave consistently wrt.
BTN_TOUCH.

Signed-off-by: Jochen Friedrich <[e-mail]>
Acked-by: Dmitry Torokhov <[e-mail]>
Signed-off-by: Samuel Ortiz <[e-mail]>

drivers/mfd/ucb1x00-ts.c

···
 	input_report_abs(idev, ABS_X, x);
 	input_report_abs(idev, ABS_Y, y);
 	input_report_abs(idev, ABS_PRESSURE, pressure);
+	input_report_key(idev, BTN_TOUCH, 1);
 	input_sync(idev);
 }
 
···
 	struct input_dev *idev = ts->idev;
 
 	input_report_abs(idev, ABS_PRESSURE, 0);
+	input_report_key(idev, BTN_TOUCH, 0);
 	input_sync(idev);
 }
 
···
 	idev->open       = ucb1x00_ts_open;
 	idev->close      = ucb1x00_ts_close;
 
-	__set_bit(EV_ABS, idev->evbit);
+	idev->evbit[0]   = BIT_MASK(EV_ABS) | BIT_MASK(EV_KEY);
+	idev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);
 
 	input_set_drvdata(idev, ts);