net/ipv4: Add extack message that dev is required for ONLINK

Make IPv4 consistent with IPv6 and return an extack message that the
ONLINK flag requires a nexthop device.

Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David Ahern 2018-08-29 16:53:27 -07:00 • committed by David S. Miller
commit 066b103008