pinctrl/mediatek: fix spelling mistake in dev_err error message

Trivial change, fix spelling mistake 'invaild' -> 'invalid' in
dev_err message.
Signed-off-by: NColin Ian King <colin.king@canonical.com>
Acked-by: NHongzhou Yang <hongzhou.yang@mediatek.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/mediatek/pinctrl-mtk-common.c

@@ -702,7 +702,7 @@ static int mtk_pmx_set_mux(struct pinctrl_dev *pctldev,
 
 	ret = mtk_pctrl_is_function_valid(pctl, g->pin, function);
 	if (!ret) {
-		dev_err(pctl->dev, "invaild function %d on group %d .\n",
+		dev_err(pctl->dev, "invalid function %d on group %d .\n",
 				function, group);
 		return -EINVAL;
 	}