owners: add drivers/net/vxlan/ to networking

The vxlan implementation has been moved from drivers/net/vxlan.c to drivers/net/vxlan/*, but we only have an entry for the old path in owners.yaml.

get_maintainers.pl doesn't seem to recognize that drivers/net/vxlan* should match drivers/net/vxlan/, so add a separate entry.

Signed-off-by: Sabrina Dubroca sdubroca@redhat.com