drm/gma500: Fix null dereference in hdmi teardown

pci_set_drvdata sets the value of pdev->driver_data to NULL,
after which the driver_data obtained from the same dev is
dereferenced in oaktrail_hdmi_i2c_exit, and the i2c_dev is
extracted from it. To prevent this, swap these calls.

Found by Linux Verification Center (linuxtesting.org) with Svacer.

Fixes: 1b082cc ("gma500: Add Oaktrail support")
Signed-off-by: Zabelin Nikita <[email protected]>
Signed-off-by: Patrik Jakobsson <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

Author: Zabelin Nikita

drivers/gpu/drm/gma500/oaktrail_hdmi.c

@@ -726,8 +726,8 @@ void oaktrail_hdmi_teardown(struct drm_device *dev)
 
 	if (hdmi_dev) {
 		pdev = hdmi_dev->dev;
-		pci_set_drvdata(pdev, NULL);
 		oaktrail_hdmi_i2c_exit(pdev);
+		pci_set_drvdata(pdev, NULL);
 		iounmap(hdmi_dev->regs);
 		kfree(hdmi_dev);
 		pci_dev_put(pdev);