drm/i915: add new intel audio file to group DP/HDMI audio

In preparation for some additional cleanup. No functional changes.

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
index 9c646c6..891e584 100644
--- a/drivers/gpu/drm/i915/Makefile
+++ b/drivers/gpu/drm/i915/Makefile
@@ -44,7 +44,8 @@
 	  intel_renderstate_gen9.o
 
 # modesetting core code
-i915-y += intel_bios.o \
+i915-y += intel_audio.o \
+	  intel_bios.o \
 	  intel_display.o \
 	  intel_fifo_underrun.o \
 	  intel_frontbuffer.o \