drm/i915: Make intel_enable_fbc() static

This function has no user outside of intel_pm.c.

Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 346bde1..e0de8b3 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -368,7 +368,7 @@
 	dev_priv->fbc_work = NULL;
 }
 
-void intel_enable_fbc(struct drm_crtc *crtc, unsigned long interval)
+static void intel_enable_fbc(struct drm_crtc *crtc, unsigned long interval)
 {
 	struct intel_fbc_work *work;
 	struct drm_device *dev = crtc->dev;