Remove the type parameter to NetEq::GetAudio

The type is included in the AudioFrame output parameter.

Rename the type NetEqOutputType to just OutputType, since it is now
internal to NetEq.

BUG=webrtc:5607

Review URL: https://codereview.webrtc.org/1769883002

Cr-Commit-Position: refs/heads/master@{#11903}
diff --git a/webrtc/modules/audio_coding/acm2/acm_receiver.cc b/webrtc/modules/audio_coding/acm2/acm_receiver.cc
index 1990768..5649f07 100644
--- a/webrtc/modules/audio_coding/acm2/acm_receiver.cc
+++ b/webrtc/modules/audio_coding/acm2/acm_receiver.cc
@@ -137,8 +137,7 @@
   // Accessing members, take the lock.
   rtc::CritScope lock(&crit_sect_);
 
-  enum NetEqOutputType type;
-  if (neteq_->GetAudio(audio_frame, &type) != NetEq::kOK) {
+  if (neteq_->GetAudio(audio_frame) != NetEq::kOK) {
     LOG(LERROR) << "AcmReceiver::GetAudio - NetEq Failed.";
     return -1;
   }