drm/tegra: Constify function pointer structs

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

drivers/gpu/drm/tegra/tegra-drm.ko:
-.rodata 13672
+.rodata 13684
-.data 1108
+.data 1096

Signed-off-by: Ville Syrjälä <[e-mail]>
Reviewed-by: Alex Deucher <[e-mail]>
Signed-off-by: Thierry Reding <[e-mail]>
Signed-off-by: Boris Brezillon <[e-mail]>
Link: http://patchwork.freedesktop.org/patch/msgid/[e-mail]
Signed-off-by: Daniel Vetter <[e-mail]>

drivers/gpu/drm/tegra/fb.c

···
 	return drm_gem_handle_create(file, &fb->planes[0]->gem, handle);
 }
 
-static struct drm_framebuffer_funcs tegra_fb_funcs = {
+static const struct drm_framebuffer_funcs tegra_fb_funcs = {
 	.destroy = tegra_fb_destroy,
 	.create_handle = tegra_fb_create_handle,
 };