drm/sti: Constify function pointer structs

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

 drivers/gpu/drm/sti/sticompositor.ko:
-.text                       12216
+.text                       12212
-.rodata                      1284
+.rodata                      1400
-.data                         488
+.data                         372

 drivers/gpu/drm/sti/sti_drv.ko:
-.rodata                      516
+.rodata                      544
-.data                        368
+.data                        340

 drivers/gpu/drm/sti/stidvo.ko:
-.text                       3356
+.text                       3348
-.rodata                      188
+.rodata                      256
-.data                        572
+.data                        504

 drivers/gpu/drm/sti/sti_hda.ko:
-.text                       3008
+.text                       3004
-.rodata                     2820
+.rodata                     2888
-.data                        684
+.data                        616

 drivers/gpu/drm/sti/stihdmi.ko:
-.text                        6988
+.text                        6980
-.rodata                      1340
+.rodata                      1408
-.data                         176
+.data                         108

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/sti/sti_crtc.c

@@ -226,7 +226,7 @@ static void sti_crtc_atomic_flush(struct drm_crtc *crtc,
 	}
 }
 
-static struct drm_crtc_helper_funcs sti_crtc_helper_funcs = {
+static const struct drm_crtc_helper_funcs sti_crtc_helper_funcs = {
 	.enable = sti_crtc_enable,
 	.disable = sti_crtc_disabling,
 	.mode_fixup = sti_crtc_mode_fixup,
@@ -338,7 +338,7 @@ void sti_crtc_disable_vblank(struct drm_device *drm_dev, unsigned int pipe)
 }
 EXPORT_SYMBOL(sti_crtc_disable_vblank);
 
-static struct drm_crtc_funcs sti_crtc_funcs = {
+static const struct drm_crtc_funcs sti_crtc_funcs = {
 	.set_config = drm_atomic_helper_set_config,
 	.page_flip = drm_atomic_helper_page_flip,
 	.destroy = sti_crtc_destroy,