[iOS] Changed ptr to const ref for RTCConfiguration initialization

BUG=webrtc:7431

Review-Url: https://codereview.webrtc.org/2794193002
Cr-Commit-Position: refs/heads/master@{#17533}
diff --git a/webrtc/sdk/objc/Framework/Classes/RTCPeerConnection.mm b/webrtc/sdk/objc/Framework/Classes/RTCPeerConnection.mm
index 7c8eb4d..311e0dd 100644
--- a/webrtc/sdk/objc/Framework/Classes/RTCPeerConnection.mm
+++ b/webrtc/sdk/objc/Framework/Classes/RTCPeerConnection.mm
@@ -291,7 +291,7 @@
 - (RTCConfiguration *)configuration {
   webrtc::PeerConnectionInterface::RTCConfiguration config =
     _peerConnection->GetConfiguration();
-  return [[RTCConfiguration alloc] initWithNativeConfiguration:&config];
+  return [[RTCConfiguration alloc] initWithNativeConfiguration:config];
 }
 
 - (void)close {