plugin: use 'data_rec_cnt' array instead separate counters

'uint64_t data_rec_cnt[SSA_TABLE_ID_MAX]' array is used
for initializing 'struct ssa_db_diff' instead of separate
bunch of counters (1 for each type of records).

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