ACPICA: Add support for PlatformRtMechanism OperationRegion handler

ACPICA commit cdf48b141d7da38e47fe4020310033ddd1971f9e

Writing a buffer to a PlatformRtMechanism FieldUnit invokes a
bidirectional transaction. The input buffer contains 26 bytes
containing 9 bytes of status, a command byte and a 16-byte UUID.
This change will will simply pass this incoming buffer to a handler
registered by the OS.

Link: https://github.com/acpica/acpica/commit/cdf48b14


Signed-off-by: Erik Kaneda <erik.kaneda@intel.com>
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>