net/mlx5e: Fix TXQ indices to be sequential

[ Upstream commit c55d8b10 ]

Cited patch changed (channel index, tc) => (TXQ index) mapping to be a
static one, in order to keep indices consistent when changing number of
channels or TCs.

For 32 channels (OOB) and 8 TCs, real num of TXQs is 256.
When reducing the amount of channels to 8, the real num of TXQs will be
changed to 64.
This indices method is buggy:
- Channel #0, TC 3, the TXQ index is 96.
- Index 8 is not valid, as there is no such TXQ from driver perspective
  (As it represents channel #8, TC 0, which is not valid with the above
  configuration).

As part of driver's select queue, it calls netdev_pick_tx which returns an
index in the range of real number of TXQs. Depends on the return value,
with the examples above, driver could have returned index larger than the
real number of tx queues, or crash the kernel as it tries to read invalid
address of SQ which was not allocated.

Fix that by allocating sequential TXQ indices, and hold a new mapping
between (channel index, tc) => (real TXQ index). This mapping will be
updated as part of priv channels activation, and is used in
mlx5e_select_queue to find the selected queue index.

The existing indices mapping (channel_tc2txq) is no longer needed, as it
is used only for statistics structures and can be calculated on run time.
Delete its definintion and updates.

Fixes: 8bfaf07f ("net/mlx5e: Present SW stats when state is not opened")
Signed-off-by: Eran Ben Elisha <eranbe@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>