i386: Simplify CPUID_8000_001d for AMD

Remove all the hardcoded values and replace with generalized
fields.

Signed-off-by: Babu Moger <babu.moger@amd.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Message-Id: <159897584649.30750.3939159632943292252.stgit@naples-babu.amd.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>