net/mlx5e: Prepare for shared table to keep TC eswitch flows

This is a refactoring step to be able and store the hash table which
keeps track of offloaded TC flows in a different location for NIC
vs e-switch rules.

Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Reviewed-by: Paul Blakey <paulb@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>