Remove the preprocessor symbol WEBRTC_CODEC_AVT (it was always defined)

webrtc/modules/audio_coding/main/acm2/audio_coding_module_impl.cc

Index: webrtc/modules/audio_coding/main/acm2/audio_coding_module_impl.cc
diff --git a/webrtc/modules/audio_coding/main/acm2/audio_coding_module_impl.cc b/webrtc/modules/audio_coding/main/acm2/audio_coding_module_impl.cc
index be0fbf1d3e2817305688974b5e03711704d29317..5aa320b8b6a558b623dd55392a25a8e18f6df4d5 100644
--- a/webrtc/modules/audio_coding/main/acm2/audio_coding_module_impl.cc
+++ b/webrtc/modules/audio_coding/main/acm2/audio_coding_module_impl.cc
@@ -1130,13 +1130,11 @@ bool AudioCodingImpl::MapCodecTypeToParameters(int codec_type,
       *sample_rate_hz = 8000;
       *channels = 1;
       break;
-#ifdef WEBRTC_CODEC_AVT
     case acm2::ACMCodecDB::kAVT:
       *codec_name = "telephone-event";
       *sample_rate_hz = 8000;
       *channels = 1;
       break;
-#endif
     default:
       FATAL() << "Codec type " << codec_type << " not supported.";
   }