drm/cirrus: Remove references to struct drm_device.pdev

Using struct drm_device.pdev is deprecated. Convert cirrus to struct
drm_device.dev. No functional changes.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201201103542.2182-6-tzimmermann@suse.de

drivers/gpu/drm/tiny/cirrus.c

@@ -602,7 +602,6 @@ static int cirrus_pci_probe(struct pci_dev *pdev,
 
 	drm_mode_config_reset(dev);
 
-	dev->pdev = pdev;
 	pci_set_drvdata(pdev, dev);
 	ret = drm_dev_register(dev, 0);
 	if (ret)