msm8660: fix incorrect gpio_config in touchkey driver

  * drivers/gpio/pm8xxx-gpio.c:pm8xxx_gpio_config() does not take the
    raw GPIO number
  * fixes this error in kmsg:
    "pm8xxx_gpio_config: called on gpio 13 not handled by any pmic"

Change-Id: I78609eb6019dcabe9abfdafc6f65e7a007311185