qemu: Resolve Coverity FORWARD_NULL
qemu: Resolve Coverity FORWARD_NULL

Coverity notices that net->ifname is potentially referenced after a
VIR_FREE().  Since the net->ifname will eventually be free'd during
virDomainDefFree when calling virDomainNetDefFree, let's just that
processing take care the free.

Signed-off-by: John Ferlan <87558058f6f829e5ec976c8ef960720af4ff9c7d@redhat.com>

olafhering/libvirt,taget/libvirt,andreabolognani/libvirt,crobinso/libvirt,fabianfreyer/libvirt,VenkatDatta/libvirt,zippy2/libvirt,olafhering/libvirt,olafhering/libvirt,rlaager/libvirt,fabianfreyer/libvirt,crobinso/libvirt,nertpinx/libvirt,zippy2/libvirt,andreabolognani/libvirt,libvirt/libvirt,taget/libvirt,rlaager/libvirt,taget/libvirt,datto/libvirt,VenkatDatta/libvirt,crobinso/libvirt,zippy2/libvirt,libvirt/libvirt,zippy2/libvirt,jardasgit/libvirt,rlaager/libvirt,rlaager/libvirt,libvirt/libvirt,andreabolognani/libvirt,crobinso/libvirt,jardasgit/libvirt,VenkatDatta/libvirt,jardasgit/libvirt,nertpinx/libvirt,eskultety/libvirt,datto/libvirt,fabianfreyer/libvirt,rlaager/libvirt,andreabolognani/libvirt,jfehlig/libvirt,jfehlig/libvirt,libvirt/libvirt,nertpinx/libvirt,nertpinx/libvirt,jfehlig/libvirt,eskultety/libvirt,eskultety/libvirt,fabianfreyer/libvirt,datto/libvirt,taget/libvirt,jfehlig/libvirt,eskultety/libvirt,nertpinx/libvirt,datto/libvirt,andreabolognani/libvirt,fabianfreyer/libvirt,jardasgit/libvirt,datto/libvirt,eskultety/libvirt,olafhering/libvirt,taget/libvirt,jardasgit/libvirt,VenkatDatta/libvirt,VenkatDatta/libvirt