HMAT: Register memory-side cache after parsing

Instead of registering the HMAT cache attributes in line with parsing
the table, save the attributes in the memory target and register them
after parsing completes. This will make it easier to register the
attributes later when hot add is supported.

Tested-by: Brice Goglin <Brice.Goglin@inria.fr>
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>