net/mlx5e: Fix missing cleanup of ethtool steering during rep rx cleanup

The cited commit add initialization of ethtool steering during
representor rx initializations without cleaning it up in representor
rx cleanup, this may cause for stale ethtool flows to remain after
moving back from switchdev mode to legacy mode.

Fixed by calling ethtool steering cleanup during rep rx cleanup.

Fixes: 6783e8b2

 ("net/mlx5e: Init ethtool steering for representors")
Signed-off-by: Maor Dickman <maord@mellanox.com>
Reviewed-by: Roi Dayan <roid@mellanox.com>
Reviewed-by: Vlad Buslov <vladbu@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>