remove unnecessary double allocation

BUG=

Review-Url: https://codereview.webrtc.org/2226933005
Cr-Commit-Position: refs/heads/master@{#13744}

webrtc/sdk/objc/Framework/Classes/avfoundationvideocapturer.mm

diff --git a/webrtc/sdk/objc/Framework/Classes/avfoundationvideocapturer.mm b/webrtc/sdk/objc/Framework/Classes/avfoundationvideocapturer.mm
index 331db6d..1915538 100644
--- a/webrtc/sdk/objc/Framework/Classes/avfoundationvideocapturer.mm
+++ b/webrtc/sdk/objc/Framework/Classes/avfoundationvideocapturer.mm
@@ -414,7 +414,6 @@
     // currently supported on iPhone / iPad.
     AVCaptureVideoDataOutput *videoDataOutput =
         [[AVCaptureVideoDataOutput alloc] init];
-    videoDataOutput = [[AVCaptureVideoDataOutput alloc] init];
     videoDataOutput.videoSettings = @{
       (NSString *)kCVPixelBufferPixelFormatTypeKey :
         @(kCVPixelFormatType_420YpCbCr8BiPlanarFullRange)