pinctrl: mediatek: add generic driving setup property on mt8192

pinctrl: mediatek: add generic driving setup property on mt8192

1. The dt-binding expects that drive-strength arguments be passed
in mA, but the driver was expecting raw values. And that this
commit changes the driver so that it is aligned with the binding.
2. This commit provides generic driving setup, which support
2/4/6/8/10/12/14/16mA driving, original driver just set raw data
setup setting when use drive-strength property.

Signed-off-by: Guodong Liu <guodong.liu@mediatek.com>
Reviewed-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Tested-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Link: https://lore.kernel.org/r/20220624133700.15487-2-guodong.liu@mediatek.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>