gpio: driver for AMD Promontory

gpio: driver for AMD Promontory

This patch adds a new GPIO driver for AMD Promontory chip.

This GPIO controller is enumerated by ACPI and the ACPI compliant
hardware ID is AMDF030.

Change history:

v2: 1. fix coding style
    2. registers renaming
v3: 1. change include file
    2. fix coding style
    3. remove module_init/exit, add module_platform_driver
    4. remove MODULE_ALIAS
v4: 1. change TOTAL_GPIO_PINS to PT_TOTAL_GPIO
    2. remove PCI dependency in Kconfig
    3. fix subject line

Signed-off-by: YD Tseng <Yd_Tseng@asmedia.com.tw>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>