ssa_db.[c h]: add new method to API to determine data table count

'ssa_db_calculate_data_tbl_num()' method was added.
It is used to calcualte the number of data tables
out of table definition dataset.

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