network: allow <vlan> in type='hostdev' networks
network: allow <vlan> in type='hostdev' networks

This resolves: https://bugzilla.redhat.com/show_bug.cgi?id=999107

Although SRIOV network cards support setting a vlan tag on their
virtual functions, and although setting this vlan tag via a <vlan>
element in a domain's <interface> works, setting a vlan tag for these
devices in a <network> definition, or in a network <portgroup>
definition is also supposed to work (and the comment that validates
<vlan> usage even says that!). However, the check to allow it only
checked for an openvswitch network, so attempts to add <vlan> to a
network of type='hostdev' would fail.

(cherry pick from upstream commit
4b42e3b97f47c5b9e40a21eaecd18bc785118f63. Only conflict was that
attributes associated with forward element have been moved into a
separate object upstream, so "forward.Type" in the upstream patch was
changed to "forwardType" in the RHEL6.5 version)

mithleshvrts/libvirt-0.10.2,mithleshvrts/libvirt-0.10.2,mithleshvrts/libvirt-0.10.2,mithleshvrts/libvirt-0.10.2,mithleshvrts/libvirt-0.10.2