pinctrl: mediatek: Fix fallback call path

pinctrl: mediatek: Fix fallback call path

Some SoCs, eg. mt8183, are using a pinconfig operation bias_set_combo.
The fallback path in mtk_pinconf_adv_pull_set() should also try this
operation.

Fixes: cafe19db7751 ("pinctrl: mediatek: Backward compatible to previous Mediatek's bias-pull usage")
Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org>
Acked-by: Sean Wang <sean.wang@kernel.org>
Link: https://lore.kernel.org/r/20201228090425.2130569-1-hsinyi@chromium.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>