drm/amd/display: Use dev_get_drvdata

Instead of using to_pci_dev + pci_get_drvdata,
use dev_get_drvdata to make code simpler.
Signed-off-by: Chuhong Yuan <hslester96@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -2430,8 +2430,7 @@ static ssize_t s3_debug_store(struct device *device,
 {
 	int ret;
 	int s3_state;
-	struct pci_dev *pdev = to_pci_dev(device);
-	struct drm_device *drm_dev = pci_get_drvdata(pdev);
+	struct drm_device *drm_dev = dev_get_drvdata(device);
 	struct amdgpu_device *adev = drm_dev->dev_private;
 
 	ret = kstrtoint(buf, 0, &s3_state);