tipc: fix uninitialized value for broadcast retransmission

When sending broadcast message on high load system, there are a lot of
unnecessary packets restranmission. That issue was caused by missing in
initial criteria for retransmission.

To prevent this happen, just initialize this criteria for retransmission
in next 10 milliseconds.

Fixes: 31c4f4cc ("tipc: improve broadcast retransmission algorithm")
Acked-by: Ying Xue <ying.xue@windriver.com>
Acked-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: Hoang Le <hoang.h.le@dektech.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>