Kickr mutex for thread safety

Ensure the member variables are only maintained in
one thread at a time.

src/Kickr.cpp

@@ -100,7 +100,9 @@ double Kickr::getGradient()
 void
 Kickr::getRealtimeData(RealtimeData &rtData)
 {
+    pvars.lock();
     rtData = rt;
+    pvars.unlock();
 }
 
 int
@@ -149,12 +151,14 @@ void Kickr::run()
         msleep(100);
 
         if (WFApi::getInstance()->hasData()) {
+            pvars.lock();
             WFApi::getInstance()->getRealtimeData(&rt);
 
             // set speed from wheelRpm and configured wheelsize
             double x = rt.getWheelRpm();
             if (devConf) rt.setSpeed(x * (devConf->wheelSize/1000) * 60 / 1000);
             else rt.setSpeed(x * 2.10 * 60 / 1000);
+            pvars.unlock();
         }
     }