Cleanup unused logic for ProducerBuffer.Detach

ProducerBuffer.Detach is disabled during migration. Therefore, related
pdx rpc code is no longer needed and could be removed. This is also
required to move BufferNode off IonBuffer, as one of the constructor of
BufferNode is called inside these code.

Test: "atest buffer_hub-test" passed.
Bug: 112338294
Change-Id: I950a2d0f59362f217636da9310f7bfff23127092
diff --git a/services/vr/bufferhubd/producer_channel.cpp b/services/vr/bufferhubd/producer_channel.cpp
index beedc4c..2b82fc5 100644
--- a/services/vr/bufferhubd/producer_channel.cpp
+++ b/services/vr/bufferhubd/producer_channel.cpp
@@ -216,11 +216,6 @@
           *this, &ProducerChannel::OnProducerGain, message);
       return true;
 
-    case BufferHubRPC::ProducerBufferDetach::Opcode:
-      DispatchRemoteMethod<BufferHubRPC::ProducerBufferDetach>(
-          *this, &ProducerChannel::OnProducerDetach, message);
-      return true;
-
     default:
       return false;
   }
@@ -403,7 +398,9 @@
   return {std::move(returned_fence_)};
 }
 
-Status<RemoteChannelHandle> ProducerChannel::OnProducerDetach(
+// TODO(b/112338294) Keep here for reference. Remove it after new logic is
+// written.
+/* Status<RemoteChannelHandle> ProducerChannel::OnProducerDetach(
     Message& message) {
   ATRACE_NAME("ProducerChannel::OnProducerDetach");
   ALOGD_IF(TRACE, "ProducerChannel::OnProducerDetach: buffer_id=%d",
@@ -455,7 +452,7 @@
   }
 
   return status;
-}
+} */
 
 Status<LocalFence> ProducerChannel::OnConsumerAcquire(Message& /*message*/) {
   ATRACE_NAME("ProducerChannel::OnConsumerAcquire");