net: ipv4: Do not drop to make_route if oif is l3mdev

net: ipv4: Do not drop to make_route if oif is l3mdev

Commit 41c4a006031b was a bit aggressive removing l3mdev calls in
the IPv4 stack. If the fib_lookup fails we do not want to drop to
make_route if the oif is an l3mdev device.

Also reverts e8705c9f22e8 ("net: l3mdev: Remove netif_index_is_l3_master")
which removed netif_index_is_l3_master.

Fixes: 41c4a006031b ("net: l3mdev: remove redundant calls")
Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>