drm/armada: Constify function pointer structs

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

drivers/gpu/drm/armada/armada.ko:
-.rodata                      1040
+.rodata                      1100
-.data                        1156
+.data                        1096
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Signed-off-by: NThierry Reding <treding@nvidia.com>
Signed-off-by: NBoris Brezillon <boris.brezillon@free-electrons.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1450178476-26284-12-git-send-email-boris.brezillon@free-electrons.comSigned-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/armada/armada_crtc.c

@@ -1074,7 +1074,7 @@ armada_drm_crtc_set_property(struct drm_crtc *crtc,
 	return 0;
 }
 
-static struct drm_crtc_funcs armada_crtc_funcs = {
+static const struct drm_crtc_funcs armada_crtc_funcs = {
 	.cursor_set	= armada_drm_crtc_cursor_set,
 	.cursor_move	= armada_drm_crtc_cursor_move,
 	.destroy	= armada_drm_crtc_destroy,