slip: fix get_stats() method

Use integrated net_device_stats instead of a static one, and make sure
no transient values are feeded. ndo_get_stats() can be called by
concurrent cpus.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
1 file changed