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/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 155719f..a840cb1 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -3513,6 +3513,7 @@
 	.mode_set_base = intel_pipe_set_base,
 	.prepare = intel_crtc_prepare,
 	.commit = intel_crtc_commit,
+	.load_lut = intel_crtc_load_lut,
 };
 
 static const struct drm_crtc_funcs intel_crtc_funcs = {