gnu: vm: Remove erroneous store reference.

* gnu/system/vm.scm (system-qemu-image): Remove reference from BOOT to
  MINGETTY since MINGETTY may not be valid yet.

gnu/system/vm.scm

@@ -594,8 +594,7 @@ (define etc-rpc
            (boot    (add-text-to-store store "boot"
                                        (object->string
                                         `(execl ,dmd-file "dmd"
-                                                "--config" ,dmd-conf))
-                                       (list out)))
+                                                "--config" ,dmd-conf))))
            (entries  (list (menu-entry
                             (label (string-append
                                     "GNU System with Linux-Libre "