pinctrl: mediatek: extend struct mtk_pin_soc to pinctrl-mtk-common-v2.c

Add two parameters gpio_m and eint_m for configuring GPIO mode and EINT
mode, they might be varying depend on SoC.

Signed-off-by: Ryder.Lee <ryder.lee@mediatek.com>
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>