KVM: x86: smm: check for failures on smm entry

In the rare case of the failure on SMM entry, the KVM should at
least terminate the VM instead of going south.

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20221025124741.228045-16-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>