ssa.c: In ssa_upstream_handler, remove some unneeded code for SSA_DB_QUERY

when SSA_DB_QUERY_EPOCH_CHANGED is being returned as the response

Signed-off-by: Hal Rosenstock <hal@mellanox.com>
core.c: Make core_clean_tree() method static

Signed-off-by: Ilya Nelkenbaum <ilyan@mellanox.com>
Signed-off-by: Hal Rosenstock <hal@mellanox.com>
core.c: Move initial orphan processing to a new separate method

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