Move qmp_query_sev() & hmp_info_sev()() from monitor.c to sev.c
and make sev_get_info() static. We don't need the stub anymore,
remove it. Add a stub for hmp_info_sev().

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20211007161716.453984-22-philmd@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>