xen/x86: hook up xen_banner() also for PVH

xen/x86: hook up xen_banner() also for PVH

This was effectively lost while dropping PVHv1 code. Move the function
and arrange for it to be called the same way as done in PV mode. Clearly
this then needs re-introducing the XENFEAT_mmu_pt_update_preserve_ad
check that was recently removed, as that's a PV-only feature.

Since the string pointed at by pv_info.name describes the mode, drop
"paravirtualized" from the log message while moving the code.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/de03054d-a20d-2114-bb86-eec28e17b3b8@suse.com
Signed-off-by: Juergen Gross <jgross@suse.com>