xen: cleanup pvh leftovers from pv-only sources

There are some leftovers testing for pvh guest mode in pv-only source
files. Remove them.

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Juergen Gross <jgross@suse.com>