net/mlx5e: Remove redundant assignment

Remove redundant assignment to tun_entropy->enabled.

Addesses-Coverity-ID: 1477328 ("Unused value")
Fixes: 97417f61 ("net/mlx5e: Fix GRE key by controlling port tunnel entropy calculation")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Reviewed-by: Roi Dayan <roid@mellanox.com>
Reviewed-by: Eli Britstein <elibr@mellanox.com>
Acked-by: Leon Romanovsky <leonro@mellanox.com>
Acked-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>