The cache bits in ESMRAMC are hardcoded to 1 (=disabled) according to
the q35 mch specs. Add and use a define with this default.
While being at it also update the SMRAM default to use the name (no code
change, just makes things a bit more readable).
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>