realtek: dsa: Select counter lock based on sleeping behavior

realtek: dsa: Select counter lock based on sleeping behavior

On many architectures, retrieving the HW counters from the switch is not
potentially sleeping. This would potentially allow these architectures to
retrieve the most recent values from the HW when .get_stats64 is called.
But because of the global mutex (which may sleep on lock), this would no
longer be possible.

Reintroduce the per port counters lock which protects from parallel
writes+reads of the non-link_stat counters. The locking is made abstract by
using helpers which identify the correct locking mechanism based on the
used read methods of the SoC.

Signed-off-by: Sven Eckelmann <[email protected]>
Link: https://github.com/openwrt/openwrt/pull/20631
Signed-off-by: Hauke Mehrtens <[email protected]>