ssa.c: Avoid starting join timer if rejoin_timeout < 0

Signed-off-by: Sasha Kotchubievsky <sashakot@mellanox.com>
Signed-off-by: Hal Rosenstock <hal@mellanox.com>
[acm distrib].c: Pass umad send errors to SSA framework

Call ssa_upstream_mad function even if umad.status != 0

Signed-off-by: Sasha Kotchubievsky <sashakot@mellanox.com>
Signed-off-by: Hal Rosenstock <hal@mellanox.com>