drm/i915: split clock gating init into per-chipset functions

This helps contain the mess to init_display() instead.

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Reviewed-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Keith Packard <keithp@keithp.com>
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 0cf65a4..581395e 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -209,12 +209,12 @@
 			     int x, int y,
 			     struct drm_framebuffer *old_fb);
 	void (*fdi_link_train)(struct drm_crtc *crtc);
+	void (*init_clock_gating)(struct drm_device *dev);
 	/* clock updates for mode set */
 	/* cursor updates */
 	/* render clock increase/decrease */
 	/* display clock increase/decrease */
 	/* pll clock increase/decrease */
-	/* clock gating init */
 };
 
 struct intel_device_info {