drm/gma500: use to_pci_dev()

Use to_pci_dev() instead of open-coding it.
Signed-off-by: Geliang Tang <geliangtang@163.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/gma500/power.c

@@ -187,7 +187,7 @@ static bool gma_resume_pci(struct pci_dev *pdev)
  */
 int gma_power_suspend(struct device *_dev)
 {
-	struct pci_dev *pdev = container_of(_dev, struct pci_dev, dev);
+	struct pci_dev *pdev = to_pci_dev(_dev);
 	struct drm_device *dev = pci_get_drvdata(pdev);
 	struct drm_psb_private *dev_priv = dev->dev_private;
 
@@ -214,7 +214,7 @@ int gma_power_suspend(struct device *_dev)
  */
 int gma_power_resume(struct device *_dev)
 {
-	struct pci_dev *pdev = container_of(_dev, struct pci_dev, dev);
+	struct pci_dev *pdev = to_pci_dev(_dev);
 	struct drm_device *dev = pci_get_drvdata(pdev);
 
 	mutex_lock(&power_mutex);