hw/i386/sev: Use legacy SEV VM types for older machine types

hw/i386/sev: Use legacy SEV VM types for older machine types

Newer 9.1 machine types will default to using the KVM_SEV_INIT2 API for
creating SEV/SEV-ES going forward. However, this API results in guest
measurement changes which are generally not expected for users of these
older guest types and can cause disruption if they switch to a newer
QEMU/kernel version. Avoid this by continuing to use the older
KVM_SEV_INIT/KVM_SEV_ES_INIT APIs for older machine types.

Signed-off-by: Michael Roth <michael.roth@amd.com>
Message-ID: <20240409230743.962513-4-michael.roth@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>