ipvs: fix timer in get_curr_sync_buff

 	Fix get_curr_sync_buff to keep buffer for 2 seconds
as intended, not just for the current jiffie. By this way
we will sync more connection structures with single packet.

Signed-off-by: Tinggong Wang <wangtinggong@gmail.com>
Signed-off-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Simon Horman <horms@verge.net.au>