separator: kill that useless thing

Just use the format strings dude. :)

config.def.h

@@ -45,7 +45,6 @@ static const char unknown_str[] = "n/a";
  * ram_total           total memory size in GB         NULL
  * ram_used            used memory in GB               NULL
  * run_command         custom shell command            command (echo foo)
- * separator           string to echo                  NULL
  * swap_free           free swap in GB                 NULL
  * swap_perc           swap usage in percent           NULL
  * swap_total          total swap size in GB           NULL