audio_rtp_session: fix setMuted

Regression was caused by 37125acf where the mute button didn't
work anymore.

Change-Id: I7e3d0953e65848818c9dc0e348759dce63274337

src/media/audio/audio_rtp_session.cpp

@@ -213,6 +213,8 @@ AudioRtpSession::setMuted(bool isMuted)
 {
     std::lock_guard<std::recursive_mutex> lock(mutex_);
     muteState_ = isMuted;
+    if (audioInput_)
+        audioInput_->setMuted(isMuted);
 }
 
 bool