gpt-auto-generator: do not write "noauto" in unit options

"auto"/"noauto" only make sense in the fstab. Putting them in Options= in the
generated unit has no effect and is confusing.

src/gpt-auto-generator/gpt-auto-generator.c

@@ -358,23 +358,19 @@ static int add_automount(
 
         _cleanup_free_ char *unit = NULL, *p = NULL;
         _cleanup_fclose_ FILE *f = NULL;
-        const char *opt = "noauto";
         int r;
 
         assert(id);
         assert(where);
         assert(description);
 
-        if (options)
-                opt = strjoina(options, ",", opt);
-
         r = add_mount(id,
                       what,
                       where,
                       fstype,
                       rw,
                       growfs,
-                      opt,
+                      options,
                       description,
                       NULL);
         if (r < 0)