dt-bindings: pinctrl: mt8192: Add drive-strength-microamp

Commit e5fabbe4 ("pinctrl: mediatek: paris: Support generic
PIN_CONFIG_DRIVE_STRENGTH_UA") added support for using
drive-strength-microamp instead of mediatek,drive-strength-adv.

Since there aren't any users of mediatek,drive-strength-adv on mt8192
yet, remove this property and add drive-strength-microamp in its place,
which has a clearer meaning.

Fixes: 4ac68333

 ("dt-bindings: pinctrl: mt8192: Add mediatek,drive-strength-adv property")
Signed-off-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogiocchino.delregno@collabora.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220525155714.1837360-2-nfraprado@collabora.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>