xen/pvh: set xen_domain_type to HVM in xen_pvh_init

commit c9f804d64bb93c8dbf957df1d7e9de11380e522d upstream.

Or else xen_domain() returns false despite xen_pvh being set.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: stable@vger.kernel.org # 4.19+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>