Only two ioctls have to be modified; the address space id is
placed in the higher 16 bits of their slot id argument.

As of this patch, no architecture defines more than one
address space; x86 will be the first.
Reviewed-by: NRadim Krčmář <rkrcmar@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>