net/mlx5: Create TC-miss priority and table

In order to adhere to kernel software datapath model bridge offloads must
come after TC and NF FDBs. Following patches in this series add new FDB
priority for bridge after FDB_FT_OFFLOAD. However, since netfilter offload
is implemented with unmanaged tables, its miss path is not automatically
connected to next priority and requires the code to manually connect with
slow table. To keep bridge offloads encapsulated and not mix it with
eswitch offloads, create a new FDB_TC_MISS priority between FDB_FT_OFFLOAD
and FDB_SLOW_PATH:

          +
          |
+---------v----------+
|                    |
|   FDB_TC_OFFLOAD   |
|                    |
+---------+----------+
          |
          |
          |
+---------v----------+
|                    |
|   FDB_FT_OFFLOAD   |
|                    |
+---------+----------+
          |
          |
          |
+---------v----------+
|                    |
|    FDB_TC_MISS     |
|                    |
+---------+----------+
          |
          |
          |
+---------v----------+
|                    |
|   FDB_SLOW_PATH    |
|                    |
+---------+----------+
          |
          v

Initialize the new priority with single default empty managed table and use
the table as TC/NF miss patch instead of slow table. This approach allows
bridge offloads to be created as new FDB namespace priority between
FDB_TC_MISS and FDB_SLOW_PATH without exposing its internal tables to any
other modules since miss path of managed TC-miss table is automatically
wired to next priority.

Signed-off-by: Vlad Buslov <vladbu@nvidia.com>
Reviewed-by: Jianbo Liu <jianbol@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>