net/mlx5e: IPoIB, Initialize max_opened_tc in mlx5i_init flow

mainline inclusion
from mainline-4.20
commit 6dae6f06
category: bugfix
bugzilla: 6101
CVE: NA

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Enhanced ipoib does not initialize max_opened_tc causing wrong ethtool
statistics. As mlx5e_grp_sw_update_stats relies on this variable, without
this change, the TX statistics will not be updated.

Fixes: 05909bab ("net/mlx5e: Avoid reset netdev stats on configuration changes")
Signed-off-by: Feras Daoud <ferasda@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Keefe LIU <liuqifa@huawei.com>
Reviewed-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>