net/mlx5e: TX, Improve performance under GSO workload

__netdev_tx_sent_queue() was introduced by:
commit 3e59020a ("net: bql: add __netdev_tx_sent_queue()")

BQL counters should be updated without flipping/caring about
BQL status, if the current skb has xmit_more set.

Using __netdev_tx_sent_queue() avoids messing with BQL stop
flag, increases performance on GSO workload by keeping
doorbells to the minimum required and also sparing atomic
operations.

Signed-off-by: Erez Alfasi <ereza@mellanox.com>
Reviewed-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>