drm/i915/audio: constify hdmi audio clock struct

Const is good.
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>

drivers/gpu/drm/i915/intel_audio.c

@@ -28,7 +28,7 @@
 #include "intel_drv.h"
 #include "i915_drv.h"
 
-static struct {
+static const struct {
 	int clock;
 	u32 config;
 } hdmi_audio_clock[] = {