pinctrl: add drive for I2C related pins on MT8183

This patch provides the advanced drive for I2C used pins on MT8183.
The detail strength specification description of the I2C pin:
When E1=0/E0=0, the strength is 0.125mA.
When E1=0/E0=1, the strength is 0.25mA.
When E1=1/E0=0, the strength is 0.5mA.
When E1=1/E0=1, the strength is 1mA.
For I2C pins, there are existing generic driving setup and the above
specific driving setup. I2C pins can only support 2/4/6/8/10/12/14/16mA
driving adjustment in generic driving setup. But in specific driving
setup, they can support 0.125/0.25/0.5/1mA adjustment.
If we enable specific driving setup for I2C pins,
the existing generic driving setup will be disabled.
For some special features, we need the I2C pins specific driving setup.
The specific driving setup is controlled by E1E0EN.
So we need add extra vendor driving preperty instead of the generic
driving property. We can add "mediatek,drive-strength-adv = <XXX>;"
to describe the specific driving setup property.
"XXX" means the value of E1E0EN. So the valid arguments of
"mediatek,drive-strength-adv" are from 0 to 7.

Signed-off-by: Zhiyong Tao <zhiyong.tao@mediatek.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>