gpio: gpio-wcove: fix GPIO IRQ status mask

According to Whiskey Cove PMIC spec, bit 7 of GPIOIRQ0_REG belongs to
battery IO. So we should skip this bit when checking for GPIO IRQ pending
status. Otherwise, wcove_gpio_irq_handler() might go into the infinite
loop until IRQ "pending" status becomes 0. This patch fixes this issue.

Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Acked-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>