ssa_db_helper.c: Eliminate compilation warnings (if compiled with -Wunused-but-set-variable)

The following compilation warnings are eliminated:

src/ssa_db_helper.c: In function âssa_db_db_def_loadâ:
src/ssa_db_helper.c:132:6: warning: variable âresâ set but not used [-Wunused-but-set-variable]
src/ssa_db_helper.c: In function âssa_db_table_def_loadâ:
src/ssa_db_helper.c:149:6: warning: variable âresâ set but not used [-Wunused-but-set-variable]
src/ssa_db_helper.c: In function âssa_db_dataset_loadâ:
src/ssa_db_helper.c:164:6: warning: variable âresâ set but not used [-Wunused-but-set-variable]
src/ssa_db_helper.c: In function âssa_db_field_tbl_loadâ:
src/ssa_db_helper.c:184:6: warning: variable âresâ set but not used [-Wunused-but-set-variable]

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