net/mlx5: E-Switch, Protect from invalid memory access in offload fdb table

The esw offloads structures share a union with the legacy mode structs.
Reset the offloads struct to zero in init to protect from null
assumptions made by the legacy mode code.
Signed-off-by: Roi Dayan <roid@mellanox.com>
Reviewed-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>

drivers/net/ethernet/mellanox/mlx5/core/eswitch_offloads.c

@@ -1611,6 +1611,7 @@ static int esw_offloads_steering_init(struct mlx5_eswitch *esw, int nvports)
 {
 	int err;
 
+	memset(&esw->fdb_table.offloads, 0, sizeof(struct offloads_fdb));
 	mutex_init(&esw->fdb_table.offloads.fdb_prio_lock);
 
 	err = esw_create_offloads_fdb_tables(esw, nvports);