ASoC: rt5677: Add ACPI support

The Chromebook Pixel 2015 uses this codec with the ACPI ID RT5677CE, but
does not use the standard DT property names so add a new function to
parse the codec properties from these ACPI properties.

Also, the GPIOs are only available by index, so we need to register a
mapping to allow machine drivers to access the GPIOs by name.

Signed-off-by: John Keeping <john@metanate.com>
Tested-by: Tom Rini <trini@konsulko.com>
Signed-off-by: Mark Brown <broonie@kernel.org>