Unify VMX and SVM code by moving APICv/AVIC enablement tracking to common
'enable_apicv' variable. Note: unlike APICv, AVIC is disabled by default.

No functional change intended.
Suggested-by: NSean Christopherson <seanjc@google.com>
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20210609150911.1471882c-2-vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>