ehea: Remove unnecessary memset of stats in netdev private data

The memory for netdev private data is allocated using kzalloc/vzalloc in
alloc_netdev_mqs, thus there is no need to zero the stats portion of it
again in the driver's probe function.

In any case, the size for the memset is wrong as the stats member is of
type rtnl_link_stats64, not net_device_stats.

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