audio: rename hardware store to backend

Use a consistent friendly name for the HWVoiceOut and HWVoiceIn
structures.

Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Volker Rümelin <vr_qemu@t-online.de>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20230121094735.11644-3-vr_qemu@t-online.de>
diff --git a/audio/audio_template.h b/audio/audio_template.h
index f0ef262..33af42ed 100644
--- a/audio/audio_template.h
+++ b/audio/audio_template.h
@@ -529,8 +529,8 @@
         HW *hw = sw->hw;
 
         if (!hw) {
-            dolog ("Internal logic error voice `%s' has no hardware store\n",
-                   SW_NAME (sw));
+            dolog("Internal logic error: voice `%s' has no backend\n",
+                  SW_NAME(sw));
             goto fail;
         }