Support receiving DTMF for multiple RTP clock rates.

BUG=webrtc:2795

Review-Url: https://codereview.webrtc.org/2337473002
Cr-Commit-Position: refs/heads/master@{#15128}
diff --git a/webrtc/modules/audio_coding/neteq/neteq_impl.cc b/webrtc/modules/audio_coding/neteq/neteq_impl.cc
index 8019e19..0fcd842 100644
--- a/webrtc/modules/audio_coding/neteq/neteq_impl.cc
+++ b/webrtc/modules/audio_coding/neteq/neteq_impl.cc
@@ -480,7 +480,7 @@
   ci.pltype = payload_type;
   std::strncpy(ci.plname, di->get_name().c_str(), sizeof(ci.plname));
   ci.plname[sizeof(ci.plname) - 1] = '\0';
-  ci.plfreq = di->IsRed() || di->IsDtmf() ? 8000 : di->SampleRateHz();
+  ci.plfreq = di->IsRed() ? 8000 : di->SampleRateHz();
   AudioDecoder* const decoder = di->GetDecoder();
   ci.channels = decoder ? decoder->Channels() : 1;
   return rtc::Optional<CodecInst>(ci);