ACPI / PMIC: Split out Kconfig and Makefile specific for ACPI PMIC

It's a bit better to maintain and allows to avoid mistakes in the future
with PMIC OpRegion drivers, if we split out Kconfig and Makefile
for ACPI PMIC to its own folder.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>