ssa_extract.[h c]: remove unnecessary 'ssa_db_remove()' method

'ssa_db_remove()' functionality already included
in 'ssa_db_extract_delete()' so it is useless.

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