ip: Support filter links/neighs with no master

ip: Support filter links/neighs with no master

Commit d3432bf10f17 ("net: Support filtering interfaces on no master")
in the kernel added support for filtering interfaces/neighbours that
have no master interface.

This patch completes it and adds this support to iproute2:
1. ip link show nomaster
2. ip address show nomaster
3. ip neighbour {show | flush} nomaster

Signed-off-by: Lahav Schlesinger <lschlesinger@drivenets.com>
Signed-off-by: David Ahern <dsahern@gmail.com>