pinctrl: mediatek: paris: Fix PIN_CONFIG_BIAS_* readback

pinctrl: mediatek: paris: Fix PIN_CONFIG_BIAS_* readback

When reading back pin bias settings, if the pin is not in the
corresponding bias state, the function should return -EINVAL.

Fix this in the mediatek-paris pinctrl library so that the read back
state is not littered with bogus a "input bias disabled" combined with
"pull up" or "pull down" states.

Fixes: 805250982bb5 ("pinctrl: mediatek: add pinctrl-paris that implements the vendor dt-bindings")
Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20220308100956.2750295-3-wenst@chromium.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>