staging: drm/imx: ipuv3-crtc: immediately update crtc->fb in ipu_page_flip

Since commit 8cf1e981
("drm: Add consistency check for page-flipping") drm_mode_page_flip_ioctl
contains a WARN_ON that triggers if the .page_flip callback didn't update
the crtc->fb pointer to the new framebuffer immediately.
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/imx-drm/ipuv3-crtc.c

@@ -147,6 +147,7 @@ static int ipu_page_flip(struct drm_crtc *crtc,
 
 	ipu_crtc->newfb = fb;
 	ipu_crtc->page_flip_event = event;
+	crtc->fb = fb;
 
 	return 0;
 }
@@ -329,7 +330,6 @@ static irqreturn_t ipu_irq_handler(int irq, void *dev_id)
 	imx_drm_handle_vblank(ipu_crtc->imx_crtc);
 
 	if (ipu_crtc->newfb) {
-		ipu_crtc->base.fb = ipu_crtc->newfb;
 		ipu_crtc->newfb = NULL;
 		ipu_drm_set_base(&ipu_crtc->base, 0, 0);
 		ipu_crtc_handle_pageflip(ipu_crtc);