conf: node_device: refactor CSS formatting
conf: node_device: refactor CSS formatting

Move XML formatting code into a new method.

Signed-off-by: Boris Fiuczynski <2648abdd55bfebf313fd324b464b047e6eea300e@linux.ibm.com>
Reviewed-by: Marc Hartmayer <7bafc8cd4e6394916d396e4f8cde69753be8d066@linux.ibm.com>
Reviewed-by: Bjoern Walk <40545c009452f40d2ae0bbfbd987b332d274d328@linux.ibm.com>
Signed-off-by: Ján Tomko <4cab11cfb98d3c937327354a78eb07dbb6ee2bc6@redhat.com>
Reviewed-by: Ján Tomko <4cab11cfb98d3c937327354a78eb07dbb6ee2bc6@redhat.com>

jfehlig/libvirt,nertpinx/libvirt,crobinso/libvirt,jfehlig/libvirt,olafhering/libvirt,crobinso/libvirt,olafhering/libvirt,nertpinx/libvirt,libvirt/libvirt,olafhering/libvirt,jfehlig/libvirt,zippy2/libvirt,libvirt/libvirt,olafhering/libvirt,zippy2/libvirt,jfehlig/libvirt,nertpinx/libvirt,nertpinx/libvirt,zippy2/libvirt,nertpinx/libvirt,libvirt/libvirt,libvirt/libvirt,crobinso/libvirt,crobinso/libvirt,zippy2/libvirt