`tc qdisc del device x ingress` changed err code

In new kernel, operation `tc qdisc del device dummy_x ingress`
changed error code of 'no ingress exists' from EINVAL to ENOENT.

CentOS 6.5
$ ip link add dummy_ni type dummy
$ tc qdisc del dev dummy_ni ingress
RTNETLINK answers: Invalid argument

Fedora 20
$ ip link add dummy_ni type dummy
$ tc qdisc del dev dummy_ni ingress
RTNETLINK answers: No such file or directory

Now qos.py:_fresh_qdisc_conf_out() ignores ENOENT too.

Change-Id: Ic40d7bdd34212cbd63850142211e544cfe1bc97b
Signed-off-by: Petr Horáček <phoracek@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/33973
Reviewed-by: Antoni Segura Puimedon <asegurap@redhat.com>
Reviewed-by: Dan Kenigsberg <danken@redhat.com>