Remove VideoEncoder::SetChannelParameters.

The SetChannelParameters function was used when WebRTC supported decoding
with errors, which we no longer do.

This cleanup CL is related to the work tracked by 9946.

Bug: webrtc:9946
Change-Id: Id2d5ed23031388f890c42651bfbe5f79eda701e5
Reviewed-on: https://webrtc-review.googlesource.com/c/108861
Reviewed-by: Stefan Holmer <stefan@webrtc.org>
Reviewed-by: Rasmus Brandt <brandtr@webrtc.org>
Reviewed-by: Niels Moller <nisse@webrtc.org>
Reviewed-by: Sami Kalliomäki <sakal@webrtc.org>
Commit-Queue: Philip Eliasson <philipel@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#25505}

modules/video_coding/codecs/i420/include/i420.h

@@ -65,10 +65,6 @@ class I420Encoder : public VideoEncoder {
   // Return value                : WEBRTC_VIDEO_CODEC_OK if OK, < 0 otherwise.
   int Release() override;
 
-  int SetChannelParameters(uint32_t /*packetLoss*/, int64_t /*rtt*/) override {
-    return WEBRTC_VIDEO_CODEC_OK;
-  }
-
  private:
   static uint8_t* InsertHeader(uint8_t* buffer,
                                uint16_t width,