KVM: nVMX: Make event request on VMXOFF iff INIT/SIPI is pending

Explicitly check for a pending INIT/SIPI event when emulating VMXOFF
instead of blindly making an event request.  There's obviously no need
to evaluate events if none are pending.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220921003201.1441511-9-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>