[audio-utils] Move temporary into variable

llvm/llvm-project#120223 became more strict
about discarded value expressions. This CL moves the array reference
into a local variable to operate on.

Bug: 385748190
Change-Id: Iafe9ff737500c7bab8f55d3e216c5606048ab4c2
Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1179388
Reviewed-by: Justin Mattson <jmatt@google.com>
Fuchsia-Auto-Submit: Caslyn Tonelli <caslyn@google.com>
Commit-Queue: Auto-Submit <auto-submit@fuchsia-infra.iam.gserviceaccount.com>

Author: Caslyn

src/media/audio/drivers/lib/audio-utils/audio-device-stream.cc

@@ -166,8 +166,8 @@ zx_status_t AudioDeviceStream::GetUniqueId(audio_stream_cmd_get_unique_id_resp_t
   if (out_id == nullptr)
     return ZX_ERR_INVALID_ARGS;
   auto result = fidl::WireCall(stream_ch_)->GetProperties();
-  memcpy(out_id->unique_id.data, result.value().properties.unique_id().data(),
-         std::min(result.value().properties.unique_id().size(), sizeof(out_id->unique_id)));
+  auto id = result.value().properties.unique_id();
+  memcpy(out_id->unique_id.data, id.data(), std::min(id.size(), sizeof(out_id->unique_id)));
   return ZX_OK;
 }