dt-bindings: pinctrl: mt8186: Add and use drive-strength-microamp

dt-bindings: pinctrl: mt8186: Add and use drive-strength-microamp

Commit e5fabbe43f3f ("pinctrl: mediatek: paris: Support generic
PIN_CONFIG_DRIVE_STRENGTH_UA") added support for using
drive-strength-microamp instead of mediatek,drive-strength-adv.

Similarly to the mt8192 and mt8195, there's no user of property
'mediatek,drive-strength-adv', hence removing it is safe.

Fixes: 338e953f1bd1 ("dt-bindings: pinctrl: mt8186: add pinctrl file and binding document")
Signed-off-by: Allen-KH Cheng <allen-kh.cheng@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220725110702.11362-3-allen-kh.cheng@mediatek.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>