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>

drivers/gpu/drm/radeon/radeon_legacy_crtc.c

@@ -1053,6 +1053,7 @@ static const struct drm_crtc_helper_funcs legacy_helper_funcs = {
 	.mode_set_base = radeon_crtc_set_base,
 	.prepare = radeon_crtc_prepare,
 	.commit = radeon_crtc_commit,
+	.load_lut = radeon_crtc_load_lut,
 };