net/mlx5: Keep autogroups list ordered

Finding a new autogroup range is done by going over a group list
sorted by each group start index. The search is stopped after finding
the first free range. Adding the newly created group to the list is
wrongly added to the end of the list regardless of its start index as
the parameter of where to insert it is ignored.

This commit makes sure to use that unused parameter to insert
it where requested.

Fixes: f0d22d18 ('net/mlx5_core: Introduce flow steering autogrouped flow table')
Signed-off-by: Paul Blakey <paulb@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>