net/mlx5e: Correctly handle changing the number of queues when the interface is down

net/mlx5e: Correctly handle changing the number of queues when the interface is down

This commit addresses two issues related to changing the number of
queues when the channels are closed:

1. Missing call to mlx5e_num_channels_changed to update
real_num_tx_queues when the number of TCs is changed.

2. When mlx5e_num_channels_changed returns an error, the channel
parameters must be reverted.

Two Fixes: tags correspond to the first commits where these two issues
were introduced.

Fixes: 3b2549807c38 ("net/mlx5e: Fix configuration of XPS cpumasks and netdev queues in corner cases")
Fixes: be21799eda44 ("net/mlx5e: Handle errors from netif_set_real_num_{tx,rx}_queues")
Signed-off-by: Maxim Mikityanskiy <maximmi@mellanox.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>