xen/events: use xen_vcpu_id mapping for EVTCHNOP_status

xen/events: use xen_vcpu_id mapping for EVTCHNOP_status

EVTCHNOP_status hypercall returns Xen's idea of vcpu id so we need to
compare it against xen_vcpu_id mapping, not the Linux cpu id.

Suggested-by: Radim Krcmar <rkrcmar@redhat.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
OraBug: 25497392

(cherry picked from commit b36585a0a3c169612f3105139464a2da1d3ecc03)
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>