net/mlx5_core: Set priority attributes

Each priority has two attributes:
1. max_ft - maximum allowed flow tables under this priority.
2. start_level - start level range of the flow tables
in the priority.

These attributes are set by traversing the tree nodes by
DFS and set start level and max flow tables to each priority.
Start level depends on the max flow tables of the prior priorities
in the tree.

The leaves of the trees have max_ft set in them. Each node accumulates
the max_ft of its children and set it accordingly.

Signed-off-by: Maor Gottlieb <maorg@mellanox.com>
Signed-off-by: Moni Shoua <monis@mellanox.com>
Signed-off-by: Matan Barak <matanb@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>