Delete unused method NetEq::PacketBufferStatistics

Bug: None
Change-Id: I9f87e445e2b5b54f78474489172f694abff38363
Reviewed-on: https://webrtc-review.googlesource.com/c/111660
Reviewed-by: Henrik Lundin <henrik.lundin@webrtc.org>
Commit-Queue: Niels Moller <nisse@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#25766}

modules/audio_coding/neteq/packet_buffer.cc

@@ -299,9 +299,4 @@ bool PacketBuffer::ContainsDtxOrCngPacket(
   return false;
 }
 
-void PacketBuffer::BufferStat(int* num_packets, int* max_num_packets) const {
-  *num_packets = static_cast<int>(buffer_.size());
-  *max_num_packets = static_cast<int>(max_number_of_packets_);
-}
-
 }  // namespace webrtc