Fix first frame with RTT (#438)

Removing a redundant check that was introduced with the recursive update
loop fix. This prevented the first frame of an RTT scene to render all
RTT textures correctly.

Author: wouterlucas

src/core/CoreNode.ts

@@ -2159,10 +2159,6 @@ export class CoreNode extends EventEmitter {
   }
 
   setRTTUpdates(type: number) {
-    if (this.hasRTTupdates === true) {
-      return;
-    }
-
     this.hasRTTupdates = true;
     this.parent?.setRTTUpdates(type);
   }