qemuDomainAttachNetDevice: Move hostdev handling a bit further
qemuDomainAttachNetDevice: Move hostdev handling a bit further

The idea is to have function that does some checking at its
beginning and then have one big switch for all the interface
types it supports.

Signed-off-by: Michal Privoznik <83d82aaba2eed257f4814b0c239c260c4caaadf0@redhat.com>

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