ssa.c: Moved a couple of comments to slightly better location

Signed-off-by: Hal Rosenstock <hal@mellanox.com>
ssa.c: In ssa_upstream_handle_op, reset some connection fields when DB update

If previous SSA DB, reset field and data tables pointers in the
upstream connection data structure.

This may need to be based on DB update flags indicating whether it
is a full or partial update.

Now, full update is working properly on various (not all) topology changes.

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