arc_emac: Use net_device_stats from struct net_device

Instead of using a private copy of struct net_device_stats in struct
arc_emac_priv, use stats from struct net_device.

Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --cc drivers/net/ethernet/arc/emac.h
Simple merge

diff --cc drivers/net/ethernet/arc/emac_main.c
Simple merge