Commit e0d56fdd 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 19664c6a ("net: l3mdev: Remove netif_index_is_l3_master")
which removed netif_index_is_l3_master.

Fixes: e0d56fdd ("net: l3mdev: remove redundant calls")
Signed-off-by: NDavid Ahern <dsa@cumulusnetworks.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>