xsm/flask: handle XEN_DOMCTL_memory_mapping for all architectures

xsm/flask: handle XEN_DOMCTL_memory_mapping for all architectures

Currently, FLASK only handles the memory_mapping hypercall for the
x86 architecture. As the DOMCTL's hook now is in common code and
no more specific to x86, this commit lets the DOMCTL be handled also
for other architectures.

Signed-off-by: Arianna Avanzini <avanzini.arianna@gmail.com>
Reviewed-by: Julien Grall <julien.grall@citrix.com>
Acked-by: Ian Campbell <Ian.Campbell@eu.citrix.com>
Acked-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Cc: Dario Faggioli <dario.faggioli@citrix.com>
Cc: Paolo Valente <paolo.valente@unimore.it>
Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: Jan Beulich <JBeulich@suse.com>
Cc: Keir Fraser <keir@xen.org>
Cc: Tim Deegan <tim@xen.org>
Cc: Ian Jackson <Ian.Jackson@eu.citrix.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Eric Trudeau <etrudeau@broadcom.com>
Cc: Viktor Kleinik <viktor.kleinik@globallogic.com>
Cc: Andrii Tseglytskyi <andrii.tseglytskyi@globallogic.com>