gpio: gpio-wcove: fix irq pending status bit width

Whiskey cove PMIC has three GPIO banks with total number of 13 GPIO
pins. But when checking for the pending status, for_each_set_bit() uses
bit width of 7 and hence it only checks the status for first 7 GPIO pins
missing to check/clear the status of rest of the GPIO pins. This patch
fixes this issue.

Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>