* gnu/build/vm.scm (initialize-hard-disk): Use "GuixSD" as label.
* gnu/system/install.scm (installation-os): Use "GuixSD" as label.
* gnu/system/vm.scm (system-disk-image): Use "GuixSD" or "GUIXSD" as volume
label.
Co-authored-by: Ludovic Courtès <ludo@gnu.org>