Input: sentelic - only report position of first finger as ST coordinates

Report only the position of the first finger as absolute non-MT coordinates,
instead of reporting both fingers alternatively. Actual MT events are
unaffected.

This fixes horizontal and improves vertical scrolling with the touchpad.

Cc: stable@vger.kernel.org
Signed-off-by: Christophe TORDEUX <christophe@tordeux.net>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/mouse/sentelic.c

@@ -791,7 +791,7 @@ static psmouse_ret_t fsp_process_byte(struct psmouse *psmouse)
 			fsp_set_slot(dev, 0, fgrs > 0, abs_x, abs_y);
 			fsp_set_slot(dev, 1, false, 0, 0);
 		}
-		if (fgrs > 0) {
+		if (fgrs == 1 || (fgrs == 2 && !(packet[0] & FSP_PB0_MFMC_FGR2))) {
 			input_report_abs(dev, ABS_X, abs_x);
 			input_report_abs(dev, ABS_Y, abs_y);
 		}