mpd: fix compilation without AUDIO_SUPPORT

Fixes #10541

Signed-off-by: Andre Heider <a.heider@gmail.com>

sound/mpd/Makefile

@@ -148,7 +148,7 @@ MESON_ARGS += \
 	-Dwave_encoder=true \
 	-Dlibsamplerate=disabled \
 	-Dsoxr=disabled \
-	-Dalsa=$(if CONFIG_AUDIO_SUPPORT,enabled,disabled) \
+	-Dalsa=$(if $(CONFIG_AUDIO_SUPPORT),enabled,disabled) \
 	-Dao=disabled \
 	-Dhttpd=true \
 	-Djack=disabled \