net/mlx5e: Remove unneeded netif_set_real_num_tx_queues

The number of queues is now updated by mlx5e_update_netdev_queues in a
centralized way, when no channels are active. Remove an extra occurrence
of netif_set_real_num_tx_queues to prepare it for the next commit.

Signed-off-by: Maxim Mikityanskiy <maximmi@mellanox.com>
Reviewed-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>