xen/domain: Pass the full domctl_createdomain struct to create_domain()

xen/domain: Pass the full domctl_createdomain struct to create_domain()

In future patches, the structure will be extended with further information,
and this is far cleaner than adding extra parameters.

One minor tweak is that the setting of guest_type needs to be deferred until
config is known-good to dereference, but this doesn't result in any changed
behaviour as system domains never used to pass XEN_DOMCTL_CDF_hvm_guest.

Also for completeness, move the setting of d->handle into the tail of
domain_create() where it more logically should live.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Julien Grall <julien.grall@arm.com>