net/mlx5e: Don't listen to remove flows event

remove_flow_enable event isn't really needed as it will be
triggered once user and/or XFRM core explicitly asked to delete
state. In such situation, we won't be interested in any event
at all.

So don't trigger and listen to remove_flow_enable event.

Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>