ACPICA: iASL/NHLT table: "Specific Data" field support

ACPICA commit 26f8c721fb01e4a26eec8c85dffcbe950d5e61a9

Add support for optional "Specific Data" field for the optional
Linux-specific structure that appears at the end of an Endpoint
Descriptor.

Link: https://github.com/acpica/acpica/commit/26f8c721
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>