pinctrl: mediatek: add input-enable and direction setting for eint resources

pinctrl: mediatek: add input-enable and direction setting for eint resources

To use pin as eint, user should make sure that:
1. pin is set to right mode, this is done in .irq_request_resources
implementation already.
2. direction of the pin is input, which should call GPIO API to set
pin to input gpio.
We add what step 2 do to .irq_request_resources so that user doesn't
need call GPIO API any more when pin for eint usage.

Signed-off-by: Biao Huang <biao.huang@mediatek.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>