drm/fb-cma-helper: Use const for drm_framebuffer_funcs argument

drm_framebuffer_init() uses const for the drm_framebuffer_funcs
argument so use that on drm_fb_cma_alloc() and
drm_fbdev_cma_create_with_funcs() as well.

Cc: [e-mail]
Signed-off-by: Noralf Trønnes <[e-mail]>
Signed-off-by: Daniel Vetter <[e-mail]>
Link: http://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/drm_fb_cma_helper.c

···
 static struct drm_fb_cma *drm_fb_cma_alloc(struct drm_device *dev,
 	const struct drm_mode_fb_cmd2 *mode_cmd,
 	struct drm_gem_cma_object **obj,
-	unsigned int num_planes, struct drm_framebuffer_funcs *funcs)
+	unsigned int num_planes, const struct drm_framebuffer_funcs *funcs)
 {
 	struct drm_fb_cma *fb_cma;
 	int ret;
···
  */
 int drm_fbdev_cma_create_with_funcs(struct drm_fb_helper *helper,
 	struct drm_fb_helper_surface_size *sizes,
-	struct drm_framebuffer_funcs *funcs)
+	const struct drm_framebuffer_funcs *funcs)
 {
 	struct drm_fbdev_cma *fbdev_cma = to_fbdev_cma(helper);
 	struct drm_mode_fb_cmd2 mode_cmd = { 0 };

include/drm/drm_fb_cma_helper.h

···
 void drm_fbdev_cma_hotplug_event(struct drm_fbdev_cma *fbdev_cma);
 int drm_fbdev_cma_create_with_funcs(struct drm_fb_helper *helper,
 	struct drm_fb_helper_surface_size *sizes,
-	struct drm_framebuffer_funcs *funcs);
+	const struct drm_framebuffer_funcs *funcs);
 
 void drm_fb_cma_destroy(struct drm_framebuffer *fb);
 int drm_fb_cma_create_handle(struct drm_framebuffer *fb,