realtek: dsa: Refresh link_stats in .get_stats64

realtek: dsa: Refresh link_stats in .get_stats64

If an architecture doesn't need to sleep for retrieving the current
statistics from the HW, it is possible to directly retrieve the last values
from the HW when .get_stats64 is called. This avoids the stale counters
with the current refresh interval of 60 seconds.

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