net: mana: Expose additional hardware counters for drop and TC via ethtool.

net: mana: Expose additional hardware counters for drop and TC via ethtool.

Add support for reporting additional hardware counters for drop and
TC using the ethtool -S interface.

These counters include:

- Aggregate Rx/Tx drop counters
- Per-TC Rx/Tx packet counters
- Per-TC Rx/Tx byte counters
- Per-TC Rx/Tx pause frame counters

The counters are exposed using ethtool_ops->get_ethtool_stats and
ethtool_ops->get_strings. This feature/counters are not available
to all versions of hardware.

Signed-off-by: Dipayaan Roy <dipayanroy@linux.microsoft.com>
Reviewed-by: Subbaraya Sundeep <sbhatta@marvell.com>
Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
Link: https://patch.msgid.link/20250609100103.GA7102@linuxonhyperv3.guj3yctzbm1etfxqx2vob5hsef.xx.internal.cloudapp.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>