net/mlx5e: Remove hairpin write debugfs files

Per the discussion in [1], hairpin parameters will be exposed using
devlink, remove the debugfs files.

[1] https://lore.kernel.org/all/20230111194608.7f15b9a1@kernel.org/



Signed-off-by: Gal Pressman <gal@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Link: https://lore.kernel.org/all/20230222230202.523667-1-saeed@kernel.org


Signed-off-by: Jakub Kicinski <kuba@kernel.org>