Revert "MetalViewController: run a no-op DisplayLink at the target framerate so iOS won't switch to a slower rate"

This reverts commit 6010182592.

VoidLink/Metal/MetalViewController.m

@@ -18,7 +18,6 @@
     MetalView *_metalView;
     MetalVideoRenderer *_renderer;
     MetricsHandler _metricsHandler;
-    CADisplayLink *_displayLink;
 }
 
 - (nonnull instancetype)initWithFrame:(CGRect)bounds framerate:(float)framerate enableHdr:(BOOL)enableHdr metricsHandler:(MetricsHandler)metricsHandler {
@@ -91,20 +90,6 @@
     // Initialize the renderer-dependent view properties.
     view.metalLayer.pixelFormat = renderer.colorPixelFormat;
     view.metalLayer.maximumDrawableCount = 3;
-
-    // We need a no-op displaylink timer or iOS can decide to run at 60fps
-    // The overhead from this should be minimal.
-    _displayLink = [CADisplayLink displayLinkWithTarget:self selector:@selector(displayLinkHandler:)];
-    if (@available(iOS 15.0, tvOS 15.0, *)) {
-        _displayLink.preferredFrameRateRange = CAFrameRateRangeMake(_framerate, _framerate, _framerate);
-    } else {
-        _displayLink.preferredFramesPerSecond = _framerate;
-    }
-    [_displayLink addToRunLoop:[NSRunLoop currentRunLoop] forMode:NSRunLoopCommonModes];
-}
-
-- (void)displayLinkHandler:(CADisplayLink *)link {
-    // Rendering does not use DisplayLink, this exists to fool iOS into keeping us running at the desired framerate
 }
 
 - (void)waitToRenderTo:(nonnull CAMetalLayer *)layer {
@@ -139,10 +124,6 @@
 
     Log(LOG_I, @"[MetalViewController] viewDidDisappear");
 
-    if (_displayLink) {
-        [_displayLink invalidate];
-    }
-
     [_renderer shutdown];
     _renderer = nil;
 }