This reverts commit 2996e6be
and some parts of 2636dc8c.

The former one tried to implement QoS setting on bridgeless networks.
However, as discussed upstream [1], the patch is far away from being
useful in even a single case. The whole idea of network QoS is to have
aggregated limits over several interfaces. This patch is doing
completely the opposite when merging two QoS settings (from the network
and the domain interface) into one which is then set at the domain
interface itself, not the network.

The latter one is the test for the previous one. Now none of them makes
sense.

1: https://www.redhat.com/archives/libvir-list/2014-January/msg01441.html

Conflicts:
	tests/virnetdevbandwidthtest.c: New test has been introduced since
    then.