[XMP] Make volume atomic, fixed issue with invalid SetVolume received from guest

- Replaced invalid log

src/xenia/app/emulator_window.cc

@@ -688,6 +688,9 @@ void EmulatorWindow::XMPConfigDialog::OnDraw(ImGuiIO& io) {
       }
     }
 
+    volume_ =
+        emulator_window_.emulator_->audio_media_player()->GetVolume()->load();
+
     if (ImGui::SliderFloat("Audio player volume", &volume_, 0.0f, 1.0f)) {
       audio_player->SetVolume(volume_);
     }

src/xenia/app/emulator_window.h

@@ -215,7 +215,9 @@ class EmulatorWindow {
                     EmulatorWindow& emulator_window)
         : ui::ImGuiDialog(imgui_drawer), emulator_window_(emulator_window) {
       if (emulator_window_.emulator_->audio_media_player()) {
-        volume_ = emulator_window_.emulator_->audio_media_player()->GetVolume();
+        volume_ = emulator_window_.emulator_->audio_media_player()
+                      ->GetVolume()
+                      ->load();
       }
     }