found by smatch:
drivers/net/net_failover.c:65 net_failover_open() error:
we previously assumed 'primary_dev' could be null (see line 43)
Fixes: cfc80d9a1163 ("net: Introduce net_failover driver") Signed-off-by: Vasily Averin <vvs@virtuozzo.com> Signed-off-by: David S. Miller <davem@davemloft.net>