mfd: intel_soc_pmic_bxtwc: Remove second level IRQ for gpio device

Currently all PMIC GPIO domain IRQs are consumed by the same
device(bxt_wcove_gpio), so there is no need to export them as
separate interrupts. We can just export only the first level
GPIO IRQ(BXTWC_GPIO_LVL1_IRQ) as an IRQ resource and let the
GPIO device driver(bxt_wcove_gpio) handle the GPIO sub domain
IRQs based on status value of GPIO level2 interrupt status
register. Also, just using only the first level IRQ will eliminate
the bug involved in requesting only the second level IRQ and not
explicitly enable the first level IRQ. For more info on this
issue please read the details at,

https://lkml.org/lkml/2017/2/27/148



This patch also makes relevant change in Whiskey cove GPIO driver to
use only first level PMIC GPIO IRQ.

Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Acked-for-MFD-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>