MT#55942 cat: Fix maintenance file handling

The script got supported added for the maintenance file, but missed a
spot where the actual selection is performed.

Fixes: commit 948f940
Change-Id: I9d092fd99a821f6f8ce72b0f7b8c05e5ab1c25e6

scripts/cat

@@ -49,7 +49,7 @@ for t in "${CONFIG_TYPES[@]}"; do
 done
 while [ -n "${1:-}" ]; do
   case "$1" in
-    constants|config|network)
+    constants|config|network|maintenance)
       config_types[$1]=true
       shift
       ;;