xen: Drop XEN_DOMCTL_suppress_spurious_page_faults

xen: Drop XEN_DOMCTL_suppress_spurious_page_faults

This functionality is obsolete.  It was introduced by c/s 39407bed9c0 into
Xend, but never exposed in libxl.

While not explicitly limited to PV guests, this is PV-only by virtue of its
position in the pagefault handler.

Looking though the XenServer templates, this was used to work around bugs in
the 32bit RHEL/CentOS 4.{5..7} kernels (fixed in 4.8).  RHEL 4 as a major
version when out if support in 2017.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Acked-by: Wei Liu <wl@xen.org>
Reviewed-by: Jan Beulich <jbeulich@suse.com>