Until now, probing_intv is a variable in struct tipc_sock but is
always set to a constant CONN_PROBING_INTERVAL. The socket
connection is probed based on this value.

In this commit, we remove this variable and setup the socket
timer based on the constant CONN_PROBING_INTERVAL.

There is no functional change in this commit.
Acked-by: NYing Xue <ying.xue@windriver.com>
Acked-by: NJon Maloy <jon.maloy@ericsson.com>
Signed-off-by: NParthasarathy Bhuvaragan <parthasarathy.bhuvaragan@ericsson.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>