util: replace body of virNetDevMacVLanDelete() with virNetlinkDelLink()
util: replace body of virNetDevMacVLanDelete() with virNetlinkDelLink()

These two functions are identical, so no sense in having the
duplication. I resisted the temptation to replace calls to
virNetDevMacVLanDelete() with calls to virNetlinkDelLink() just in
case some mythical future platform has macvtap devices that aren't
managed with netlink (or in case we some day need to do more than just
tell the kernel to delete the device).

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