virDomainDefCollectBootOrder() is called for every item on the list
for each type of device. One of the checks it makes is to gather the
order attributes from the <boot> element of all devices, and assure
that no two devices have been given the same order.

Since (internally to libvirt, *not* in the domain XML) an <interface
type='hostdev'> is on both the list of hostdev devices and the list of
network devices, it will be counted twice, and the code that checks
for multiple devices with the same boot order will give a false
positive.

To remedy this, we make sure to return early for hostdev devices that
have a parent.type != NONE.

This was introduced in commit 5b75a4, which was first in libvirt-4.4.0.

Resolves: https://bugzilla.redhat.com/1601318Signed-off-by: NLaine Stump <laine@laine.org>
Reviewed-by: NJán Tomko <jtomko@redhat.com>