drm/nouveau: Constify function pointer structs

Moves a bunch of junk to .rodata from .data.

 drivers/gpu/drm/nouveau/nouveau.ko:
-.rodata                      105688
+.rodata                      105792
-.data                        125724
+.data                        125620

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1450178476-26284-24-git-send-email-boris.brezillon@free-electrons.com
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/nouveau/dispnv04/tvnv17.c

@@ -769,7 +769,7 @@ static void nv17_tv_destroy(struct drm_encoder *encoder)
 	kfree(tv_enc);
 }
 
-static struct drm_encoder_helper_funcs nv17_tv_helper_funcs = {
+static const struct drm_encoder_helper_funcs nv17_tv_helper_funcs = {
 	.dpms = nv17_tv_dpms,
 	.mode_fixup = nv17_tv_mode_fixup,
 	.prepare = nv17_tv_prepare,
@@ -778,14 +778,14 @@ static struct drm_encoder_helper_funcs nv17_tv_helper_funcs = {
 	.detect = nv17_tv_detect,
 };
 
-static struct drm_encoder_slave_funcs nv17_tv_slave_funcs = {
+static const struct drm_encoder_slave_funcs nv17_tv_slave_funcs = {
 	.get_modes = nv17_tv_get_modes,
 	.mode_valid = nv17_tv_mode_valid,
 	.create_resources = nv17_tv_create_resources,
 	.set_property = nv17_tv_set_property,
 };
 
-static struct drm_encoder_funcs nv17_tv_funcs = {
+static const struct drm_encoder_funcs nv17_tv_funcs = {
 	.destroy = nv17_tv_destroy,
 };