ssa_release_notes.txt: Added additional known limitations

Signed-off-by: Hal Rosenstock <hal@mellanox.com>
ssa.c: Wait for all tasks to finish before rsocket thread pool is freed

We should finish all rsocket operations scheduled before appl. closing.

Signed-off-by: Sasha Kotchubievsky <sashakot@mellanox.com>
Signed-off-by: Hal Rosenstock <hal@mellanox.com>
ssa.c: Destroy newly calculated PRDB if it's equal to previous or has wrong structure

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