use dedicate icon for unspecified kerbs, see #1077

data/presets/barrier/kerb.json

@@ -1,5 +1,5 @@
 {
-    "icon": "temaki-kerb-raised",
+    "icon": "temaki-kerb-unspecified",
     "fields": [
         "kerb/kerb_barrier",
         "tactile_paving",

interim/icons.json

@@ -619,6 +619,7 @@
     "temaki-kerb-lowered",
     "temaki-kerb-raised",
     "temaki-kerb-rolled",
+    "temaki-kerb-unspecified",
     "temaki-kitchen_sink",
     "temaki-latrine",
     "temaki-laundry",