drm: nouveau: remove dead code and pointless local lut storage

The redundant fb helpers .load_lut, .gamma_set and .gamma_get are
no longer used. Remove the dead code and hook up the crtc .gamma_set
to use the crtc gamma_store directly instead of duplicating that
info locally.

Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Peter Rosin <peda@axentia.se>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20170713162538.22788-12-peda@axentia.se

drivers/gpu/drm/nouveau/nouveau_crtc.h

@@ -61,9 +61,6 @@ struct nouveau_crtc {
 
 	struct {
 		struct nouveau_bo *nvbo;
-		uint16_t r[256];
-		uint16_t g[256];
-		uint16_t b[256];
 		int depth;
 	} lut;