drm/gm12u320: Don't use drm_device->dev_private

Upcasting using a container_of macro is more typesafe, faster and
easier for the compiler to optimize.

Acked-by: Sam Ravnborg <[e-mail]>
Reviewed-by: Hans de Goede <[e-mail]>
Signed-off-by: Daniel Vetter <[e-mail]>
Cc: Hans de Goede <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/tiny/gm12u320.c

···
 	} fb_update;
 };
 
+#define to_gm12u320(__dev) container_of(__dev, struct gm12u320_device, dev)
+
 static const char cmd_data[CMD_SIZE] = {
 	0x55, 0x53, 0x42, 0x43, 0x00, 0x00, 0x00, 0x00,
 	0x68, 0xfc, 0x00, 0x00, 0x00, 0x00, 0x10, 0xff,
···
 static void gm12u320_fb_mark_dirty(struct drm_framebuffer *fb,
 				   struct drm_rect *dirty)
 {
-	struct gm12u320_device *gm12u320 = fb->dev->dev_private;
+	struct gm12u320_device *gm12u320 = to_gm12u320(fb->dev);
 	struct drm_framebuffer *old_fb = NULL;
 	bool wakeup = false;
 
···
 				 struct drm_plane_state *plane_state)
 {
 	struct drm_rect rect = { 0, 0, GM12U320_USER_WIDTH, GM12U320_HEIGHT };
-	struct gm12u320_device *gm12u320 = pipe->crtc.dev->dev_private;
+	struct gm12u320_device *gm12u320 = to_gm12u320(pipe->crtc.dev);
 
 	gm12u320->fb_update.draw_status_timeout = FIRST_FRAME_TIMEOUT;
 	gm12u320_fb_mark_dirty(plane_state->fb, &rect);
···
 
 static void gm12u320_pipe_disable(struct drm_simple_display_pipe *pipe)
 {
-	struct gm12u320_device *gm12u320 = pipe->crtc.dev->dev_private;
+	struct gm12u320_device *gm12u320 = to_gm12u320(pipe->crtc.dev);
 
 	gm12u320_stop_fb_update(gm12u320);
 }
···
 	mutex_init(&gm12u320->fb_update.lock);
 
 	dev = &gm12u320->dev;
-	dev->dev_private = gm12u320;
 
 	ret = drmm_mode_config_init(dev);
 	if (ret)
···
 static __maybe_unused int gm12u320_resume(struct usb_interface *interface)
 {
 	struct drm_device *dev = usb_get_intfdata(interface);
-	struct gm12u320_device *gm12u320 = dev->dev_private;
+	struct gm12u320_device *gm12u320 = to_gm12u320(dev);
 
 	gm12u320_set_ecomode(gm12u320);