Input: goodix - check the 'buffer status' bit before reading data

The MSB of the first byte read via I2C at the coordinates address
indicates whether the data is valid or ready (called "buffer status" in
the datasheets) when an interrupt is raised. Previously, this bit was
ignored, which resulted in a lot of incorrect detections of "finger
removed" events.
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Acked-by: Bastien Nocera <hadess@hadess.net>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/touchscreen/goodix.c

@@ -101,6 +101,9 @@ static int goodix_ts_read_input_report(struct goodix_ts_data *ts, u8 *data)
 		return error;
 	}
 
+	if (!(data[0] & 0x80))
+		return -EAGAIN;
+
 	touch_num = data[0] & 0x0f;
 	if (touch_num > ts->max_touch_num)
 		return -EPROTO;