KVM: x86: dump_vmcs should show the effective EFER

If EFER is not being loaded from the VMCS, show the effective value by
reference to the MSR autoload list or calculation.

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Edmondson <david.edmondson@oracle.com>
Message-Id: <20210318120841.133123-5-david.edmondson@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>