pinctrl: intel: implement gpio_irq_enable

There is unexpected gpio interrupt after irq_enable. If not
implemeted gpio_irq_enable callback, irq_enable calls irq_unmask
instead. But if there was interrupt set before the irq_enable,
unmask it may trigger the unexpected interrupt. By implementing
the gpio_irq_enable callback, do interrupt status ack, the issue
has gone.

Signed-off-by: Qi Zheng <qi.zheng@intel.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Qipeng Zha <qipeng.zha@intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>