mt76: mt7915: fix possible uninitialized pointer dereference in mt7986_wmac_gpio_setup

Add default case for type switch in mt7986_wmac_gpio_setup routine in
order to avoid a possible uninitialized pointer dereference.

Fixes: 99ad32a4ca ("mt76: mt7915: add support for MT7986")
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Felix Fietkau <nbd@nbd.name>

drivers/net/wireless/mediatek/mt76/mt7915/soc.c

@@ -210,6 +210,8 @@ static int mt7986_wmac_gpio_setup(struct mt7915_dev *dev)
 		if (IS_ERR_OR_NULL(state))
 			return -EINVAL;
 		break;
+	default:
+		return -EINVAL;
 	}
 
 	ret = pinctrl_select_state(pinctrl, state);