vrrp: fix busy timer by the default parameter

Currently, default 'vrrp_statistics' is zero. Thereby
TimerEventSender() kicks VRRPRouter._EventStatisticsOut() without
waiting. Since CPU usage will be 100%, this is an unsuitable default
value.

Signed-off-by: Satoshi Kobayashi <satoshi-k@stratosphere.co.jp>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>