skinengine: Make sure logical IF operator doesn't compare a garbage value

Change-Id: I125bea3c2659326b92eec027cddf0d041f10ebda

apps/gui/skin_engine/skin_tokens.c

@@ -632,6 +632,7 @@ static const char* NOINLINE get_lif_token_value(struct gui_wps *gwps,
         }
         break;
         case DEFAULT:
+            b = -1;
             break;
     }