Unfortunately ioctl numbers are platform specific, so abstract them out
of the code so they can be overridden. As it happens x86 and s390 share
the same values, so nothing needs to change yet.
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>