l3gd20: sends data as often as we get it from the sensor

samples/l3gd20.go

@@ -15,6 +15,7 @@ func main() {
 		log.Panic(err)
 	}
 	gyro := l3gd20.New(bus, l3gd20.R250DPS)
+	gyro.Poll = 50
 	defer gyro.Close()
 
 	gyro.Start()

sensor/l3gd20/l3gd20.go

@@ -358,6 +358,7 @@ func (d *L3GD20) Start() (err error) {
 				}
 				oldTime = currTime
 			case orientations <- Orientation{x, y, z}:
+				orientations = nil
 			case waitc := <-d.closing:
 				waitc <- struct{}{}
 				close(d.orientations)