drm/cirrus: 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: Eric Anholt <[e-mail]>
Acked-by: Sam Ravnborg <[e-mail]>
Signed-off-by: Daniel Vetter <[e-mail]>
Cc: Dave Airlie <[e-mail]>
Cc: Gerd Hoffmann <[e-mail]>
Cc: Daniel Vetter <[e-mail]>
Cc: "Noralf Trønnes" <[e-mail]>
Cc: Sam Ravnborg <[e-mail]>
Cc: Eric Anholt <[e-mail]>
Cc: Thomas Zimmermann <[e-mail]>
Cc: [e-mail]
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/cirrus/cirrus.c

···
 	void __iomem		       *mmio;
 };
 
+#define to_cirrus(_dev) container_of(_dev, struct cirrus_device, dev)
+
 /* ------------------------------------------------------------------ */
 /*
  * The meat of this driver. The core passes us a mode and we have to program
···
 static int cirrus_fb_blit_rect(struct drm_framebuffer *fb,
 			       struct drm_rect *rect)
 {
-	struct cirrus_device *cirrus = fb->dev->dev_private;
+	struct cirrus_device *cirrus = to_cirrus(fb->dev);
 	void *vmap;
 	int idx, ret;
 
···
 			       struct drm_crtc_state *crtc_state,
 			       struct drm_plane_state *plane_state)
 {
-	struct cirrus_device *cirrus = pipe->crtc.dev->dev_private;
+	struct cirrus_device *cirrus = to_cirrus(pipe->crtc.dev);
 
 	cirrus_mode_set(cirrus, &crtc_state->mode, plane_state->fb);
 	cirrus_fb_blit_fullscreen(plane_state->fb);
···
 static void cirrus_pipe_update(struct drm_simple_display_pipe *pipe,
 			       struct drm_plane_state *old_state)
 {
-	struct cirrus_device *cirrus = pipe->crtc.dev->dev_private;
+	struct cirrus_device *cirrus = to_cirrus(pipe->crtc.dev);
 	struct drm_plane_state *state = pipe->plane.state;
 	struct drm_crtc *crtc = &pipe->crtc;
 	struct drm_rect rect;
···
 		return PTR_ERR(cirrus);
 
 	dev = &cirrus->dev;
-	dev->dev_private = cirrus;
 
 	cirrus->vram = devm_ioremap(&pdev->dev, pci_resource_start(pdev, 0),
 				    pci_resource_len(pdev, 0));