net: macsec: add support for getting offloaded stats

When HW offloading is enabled, offloaded stats should be used, because
s/w stats are wrong and out of sync with the HW in this case.

Signed-off-by: Dmitry Bogdanov <[email protected]>
Signed-off-by: Mark Starovoytov <[email protected]>
Signed-off-by: Igor Russkikh <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

Author: logost