drm/i915: fix sparse warnings: make symbols static

Signed-off-by: Hannes Eder <hannes@hanneseder.net>
Signed-off-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Dave Airlie <airlied@linux.ie>
diff --git a/drivers/gpu/drm/i915/intel_crt.c b/drivers/gpu/drm/i915/intel_crt.c
index 5d9c94e..dcaed34 100644
--- a/drivers/gpu/drm/i915/intel_crt.c
+++ b/drivers/gpu/drm/i915/intel_crt.c
@@ -237,7 +237,7 @@
 	.best_encoder = intel_best_encoder,
 };
 
-void intel_crt_enc_destroy(struct drm_encoder *encoder)
+static void intel_crt_enc_destroy(struct drm_encoder *encoder)
 {
 	drm_encoder_cleanup(encoder);
 }