realtek: dsa: rtl931x: Reduce HW counters polling interval

realtek: dsa: rtl931x: Reduce HW counters polling interval

Some SoC families require table access to get the HW counters. A mutex is
required for this access - which will potentially cause a sleep in the
current context. This is not always possible with .get_stats64 because it
is also called in atomic contexts.

For these SoCs, the retrieval of the current counters in .get_stats64 is
skipped and the counters are simply retrieved a lot more often from the HW.

Signed-off-by: Sven Eckelmann <se@simonwunderlich.de>
Link: https://github.com/openwrt/openwrt/pull/20631
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>