Input: Revert "Revert "synaptics - use dmax in input_mt_assign_slots""

This reverts commit 09d042a2eb90 ("Revert "Input: synaptics - use dmax in
input_mt_assign_slots"")

Now that balanced slots assignments seem to be fixed, let's re-enable the
use in synaptics.c and wait for users to complain if there are still
problems.

Signed-off-by: Benjamin Tissoires <[e-mail]>
Acked-by: Hans de Goede <[e-mail]>
Acked-by: Henrik Rydberg <[e-mail]
Signed-off-by: Dmitry Torokhov <[e-mail]>

drivers/input/mouse/synaptics.c

···
 #define X_MAX_POSITIVE 8176
 #define Y_MAX_POSITIVE 8176
 
+/* maximum ABS_MT_POSITION displacement (in mm) */
+#define DMAX 10
+
 /*****************************************************************************
  *	Stuff we need even when we do not want native Synaptics support
  ****************************************************************************/
···
 		pos[i].y = synaptics_invert_y(hw[i]->y);
 	}
 
-	input_mt_assign_slots(dev, slot, pos, nsemi, 0);
+	input_mt_assign_slots(dev, slot, pos, nsemi, DMAX * priv->x_res);
 
 	for (i = 0; i < nsemi; i++) {
 		input_mt_slot(dev, slot[i]);