net/mlx5e: Remove redundant assignment of sq->user_index

It is not needed by the mlx5 Eth driver since it has a CQ per RQ/SQ.

Signed-off-by: Achiad Shochat <achiad@mellanox.com>
Signed-off-by: Amir Vadai <amirv@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>