net/mlx5_core: Introduce flow steering autogrouped flow table

When user add rule to autogrouped flow table, we search
for flow group with the same match criteria, if we don't
find such group then we create new flow group with the
required match criteria and insert the rule to this group.

We divide the flow table into required_groups + 1,
in order to reserve a part of the flow table for rules
which don't match any existing group.

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>