drm/i915: drop unused function ptr and comments.

There was some excess comments and an unused vtbl ptr.
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/573a9366d33e2b7bd7b8215af614f03f3e562926.1632869550.git.jani.nikula@intel.com

drivers/gpu/drm/i915/i915_drv.h

@@ -409,13 +409,6 @@ struct drm_i915_display_funcs {
 	void (*crtc_disable)(struct intel_atomic_state *state,
 			     struct intel_crtc *crtc);
 	void (*commit_modeset_enables)(struct intel_atomic_state *state);
-	void (*commit_modeset_disables)(struct intel_atomic_state *state);
-
-	/* clock updates for mode set */
-	/* cursor updates */
-	/* render clock increase/decrease */
-	/* display clock increase/decrease */
-	/* pll clock increase/decrease */
 };