ACPI: Unify the parsing of address_space and ext_address_space

With the unions in place which let us identify the substructs we can
use a single parser for address_space and ext_address_space.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>