kvm does not support setting the RTC, so the correct result is -ENODEV.
Returning -1 will cause sync_cmos_clock to keep trying to set the RTC
every second.
Signed-off-by: NJason Gunthorpe <jgg@ziepe.ca>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>