drm/fb: add setcmap and fix 8-bit support.

This adds support for the setcmap api and fixes the 8bpp
support at least on radeon hardware. It adds a new load_lut
hook which can be called once the color map is setup.

Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/include/drm/drm_crtc_helper.h b/include/drm/drm_crtc_helper.h
index ef47dfd..b29e201 100644
--- a/include/drm/drm_crtc_helper.h
+++ b/include/drm/drm_crtc_helper.h
@@ -61,6 +61,9 @@
 	/* Move the crtc on the current fb to the given position *optional* */
 	int (*mode_set_base)(struct drm_crtc *crtc, int x, int y,
 			     struct drm_framebuffer *old_fb);
+
+	/* reload the current crtc LUT */
+	void (*load_lut)(struct drm_crtc *crtc);
 };
 
 struct drm_encoder_helper_funcs {