[ios] fix removal of heading view when changing user tracking modes

Author: muZZkat

platform/ios/MGLUserLocationAnnotationView.m

@@ -266,6 +266,8 @@ - (void)drawDot
     }
     else
     {
+        [_headingIndicatorLayer removeFromSuperlayer];
+        [_headingIndicatorMaskLayer removeFromSuperlayer];
         _headingIndicatorLayer = nil;
         _headingIndicatorMaskLayer = nil;
     }