Remove AMR format parameter from AudioCoder in utility

The parameter was never used.

BUG=webrtc:3520

Review URL: https://codereview.webrtc.org/1365283002

Cr-Commit-Position: refs/heads/master@{#10095}
diff --git a/webrtc/modules/utility/source/coder.h b/webrtc/modules/utility/source/coder.h
index 57eada1..a57ba86 100644
--- a/webrtc/modules/utility/source/coder.h
+++ b/webrtc/modules/utility/source/coder.h
@@ -25,13 +25,9 @@
     AudioCoder(uint32_t instanceID);
     ~AudioCoder();
 
-    int32_t SetEncodeCodec(
-        const CodecInst& codecInst,
-        ACMAMRPackingFormat amrFormat = AMRBandwidthEfficient);
+    int32_t SetEncodeCodec(const CodecInst& codecInst);
 
-    int32_t SetDecodeCodec(
-        const CodecInst& codecInst,
-        ACMAMRPackingFormat amrFormat = AMRBandwidthEfficient);
+    int32_t SetDecodeCodec(const CodecInst& codecInst);
 
     int32_t Decode(AudioFrame& decodedAudio, uint32_t sampFreqHz,
                    const int8_t* incomingPayload, size_t payloadLength);