gpiolib: acpi: Split ACPI stuff to gpiolib-acpi.h

This is a follow up to the commit

  f626d6df ("gpio: of: Break out OF-only code")

which broke down OF parts of GPIO library. Here we do the similar to ACPI.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20190730104337.21235-2-andriy.shevchenko@linux.intel.com


Signed-off-by: Linus Walleij <linus.walleij@linaro.org>