make px4::ok work, use it in px4::spin

src/platforms/nuttx/px4_nodehandle.cpp

@@ -37,27 +37,8 @@
  * PX4 Middleware Wrapper Nodehandle
  */
 #include <px4.h>
-#include <platforms/px4_nodehandle.h>
 
 namespace px4
 {
-bool task_should_exit = false;
-
-
-void NodeHandle::spinOnce() {
-	/* Loop through subscriptions, call callback for updated subscriptions */
-	uORB::SubscriptionNode *sub = _subs.getHead();
-	int count = 0;
-
-	while (sub != nullptr) {
-		if (count++ > kMaxSubscriptions) {
-			PX4_WARN("exceeded max subscriptions");
-			break;
-		}
-
-		sub->update();
-		sub = sub->getSibling();
-	}
-}
 
 }