wsp(4): Do not handle pressure on non-ForceTouch devices

They always report it value as zero breaking pressure-driven drivers
like moused(8) and xf86-input-synaptics.

MFC after:	1 week

sys/dev/usb/input/wsp.c

@@ -231,6 +231,7 @@ enum tp_type {
 
 /* list of device capability bits */
 #define	HAS_INTEGRATED_BUTTON	1
+#define	SUPPORTS_FORCETOUCH	2
 
 /* trackpad finger data block size */
 #define FSIZE_TYPE1             (14 * 2)
@@ -285,7 +286,7 @@ struct wsp_tp {
 		.delta = 0,
 	},
 	[TYPE4] = {
-		.caps = HAS_INTEGRATED_BUTTON,
+		.caps = HAS_INTEGRATED_BUTTON | SUPPORTS_FORCETOUCH,
 		.button = BUTTON_TYPE4,
 		.offset = FINGER_TYPE4,
 		.fsize = FSIZE_TYPE4,
@@ -896,7 +897,8 @@ wsp_attach(device_t dev)
 	WSP_SUPPORT_ABS(sc->sc_evdev, ABS_MT_POSITION_X, sc->sc_params->x);
 	WSP_SUPPORT_ABS(sc->sc_evdev, ABS_MT_POSITION_Y, sc->sc_params->y);
 	/* finger pressure */
-	WSP_SUPPORT_ABS(sc->sc_evdev, ABS_MT_PRESSURE, sc->sc_params->p);
+	if ((sc->sc_params->tp->caps & SUPPORTS_FORCETOUCH) != 0)
+		WSP_SUPPORT_ABS(sc->sc_evdev, ABS_MT_PRESSURE, sc->sc_params->p);
 	/* finger major/minor axis */
 	WSP_SUPPORT_ABS(sc->sc_evdev, ABS_MT_TOUCH_MAJOR, sc->sc_params->w);
 	WSP_SUPPORT_ABS(sc->sc_evdev, ABS_MT_TOUCH_MINOR, sc->sc_params->w);