net/mlx5e: Add stale counter for PCIe congestion events

net/mlx5e: Add stale counter for PCIe congestion events

This ethtool counter is meant to help with observing how many times the
congestion event was triggered but on query there was no state change.

This would help to indicate when a work item was scheduled to run too
late and in the meantime the congestion state changed back to previous
state.

While at it, do a driveby typo fix in documentation for
pci_bw_inbound_high.

Signed-off-by: Dragos Tatulea <dtatulea@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/1757237976-531416-3-git-send-email-tariqt@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>