ssa.c: Cosmetic changes

Reformatted ssa_log message call in ssa_downstream_handler
Also, commentary change in ssa_upstream_handler

Signed-off-by: Hal Rosenstock <hal@mellanox.com>
ssa.c: Handle error events for downstream connections

In ssa_downstream_handler, handle POLLERR, POLLHUP, and POLLNVAL events

Signed-off-by: Hal Rosenstock <hal@mellanox.com>
ssa.c: On client reregister event, don't close listening rsockets

in ssa_upstream_dev_event

Signed-off-by: Hal Rosenstock <hal@mellanox.com>
ssa.c: Handle error events for upstream connection

In ssa_upstream_handler, handle POLLERR, POLLHUP, and POLLNVAL events

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