We create a second, simpler, link timer function, tipc_link_timeout().
The new function  makes use of the new FSM function introduced in the
previous commit, and just like it, takes a buffer queue as parameter.
It returns an event bit field and potentially a link protocol packet
to the caller.

The existing timer function, link_timeout(), is still needed for a
while, so we redesign it to become a wrapper around the new function.
Reviewed-by: NYing Xue <ying.xue@windriver.com>
Signed-off-by: NJon Maloy <jon.maloy@ericsson.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>