touchpad: a pressure change alone needs touch processing, mark as dirty

A thumb may not move, but may change pressure so we need to process
accordingly.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>

src/evdev-mt-touchpad.c

@@ -315,6 +315,8 @@ tp_process_absolute(struct tp_dispatch *tp,
 		break;
 	case ABS_MT_PRESSURE:
 		t->pressure = e->value;
+		t->dirty = true;
+		tp->queued |= TOUCHPAD_EVENT_MOTION;
 		break;
 	}
 }