In order to instantiate a CPU subtype we will need to know which type,
so move the cpu_model splitting into cpu_x86_init().

Parameters need to be set on the X86CPU instance, so move
cpu_x86_parse_featurestr() into cpu_x86_init() as well.

This leaves cpu_x86_register() operating on the model name only.
Signed-off-by: NAndreas Färber <afaerber@suse.de>
Signed-off-by: NIgor Mammedov <imammedo@redhat.com>
Reviewed-by: NEduardo Habkost <ehabkost@redhat.com>
Signed-off-by: NAndreas Färber <afaerber@suse.de>