qemu: Move device alias assignment to separate functions
qemu: Move device alias assignment to separate functions

Let's move all the virAsprintf()-s into separate functions for
better structure of the code. Later, when somebody wants to
generate a device alias, all they need is to expose the function.

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

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