KVM: nSVM: fix condition for filtering async PF

commit a3535be7 upstream.

Async page faults have to be trapped in the host (L1 in this case),
since the APF reason was passed from L0 to L1 and stored in the L1 APF
data page.  This was completely reversed: the page faults were passed
to the guest, a L2 hypervisor.

Cc: stable@vger.kernel.org
Reviewed-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>