drm/ast: Remove reference to struct drm_device.pdev

Using struct drm_device.pdev is deprecated. Upcast with to_pci_dev()
from struct drm_device.dev to get the PCI device structure.

v9:
	* fix remaining pdev references
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Michael J. Ruhl <michael.j.ruhl@intel.com>
Fixes: ba4e0339 ("drm/ast: Fixed CVE for DP501")
Cc: KuoHsiang Chou <kuohsiang_chou@aspeedtech.com>
Cc: kernel test robot <lkp@intel.com>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Dave Airlie <airlied@redhat.com>
Cc: dri-devel@lists.freedesktop.org
Link: https://patchwork.freedesktop.org/patch/msgid/20210429105101.25667-2-tzimmermann@suse.de

drivers/gpu/drm/ast/ast_main.c

@@ -411,7 +411,6 @@ struct ast_private *ast_device_create(const struct drm_driver *drv,
 		return ast;
 	dev = &ast->base;
 
-	dev->pdev = pdev;
 	pci_set_drvdata(pdev, dev);
 
 	ast->regs = pcim_iomap(pdev, 1, 0);
@@ -453,8 +452,8 @@ struct ast_private *ast_device_create(const struct drm_driver *drv,
 
 	/* map reserved buffer */
 	ast->dp501_fw_buf = NULL;
-	if (dev->vram_mm->vram_size < pci_resource_len(dev->pdev, 0)) {
-		ast->dp501_fw_buf = pci_iomap_range(dev->pdev, 0, dev->vram_mm->vram_size, 0);
+	if (dev->vram_mm->vram_size < pci_resource_len(pdev, 0)) {
+		ast->dp501_fw_buf = pci_iomap_range(pdev, 0, dev->vram_mm->vram_size, 0);
 		if (!ast->dp501_fw_buf)
 			drm_info(dev, "failed to map reserved buffer!\n");
 	}