Input: wacom_w8001 - handle errors from input_mt_init_slots()

input_mt_init_slots() may fail and we should be handling failures properly.
Signed-off-by: Ping Cheng <pingc@wacom.com>
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/touchscreen/wacom_w8001.c

@@ -518,7 +518,13 @@ static int w8001_setup_touch(struct w8001 *w8001, char *basename,
 		w8001->pktlen = W8001_PKTLEN_TOUCH2FG;
 
 		__set_bit(BTN_TOOL_DOUBLETAP, dev->keybit);
-		input_mt_init_slots(dev, 2, 0);
+		error = input_mt_init_slots(dev, 2, 0);
+		if (error) {
+			dev_err(&w8001->serio->dev,
+				"failed to initialize MT slots: %d\n", error);
+			return error;
+		}
+
 		input_set_abs_params(dev, ABS_MT_POSITION_X,
 					0, touch.x, 0, 0);
 		input_set_abs_params(dev, ABS_MT_POSITION_Y,