unittests.cfg: Increase timeout for access test

In case of npt=0 on kvm_amd, tests run slower and timeout,
so increase the timeout. The tests then do succeed.

Signed-off-by: Mohammed Gamal <m.gamal005@gmail.com>
Message-Id: <20200806124358.4928-2-mgamal@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>