drm: Fix use-after-free in the shadow-attache exit code

This regression has been introduced in

commit b3f2333de8e81b089262b26d52272911523e605f
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Wed Dec 11 11:34:31 2013 +0100

    drm: restrict the device list for shadow attached drivers

Reported-by: Dave Jones <davej@redhat.com>
Cc: Dave Jones <davej@redhat.com>
Cc: Dave Airlie <airlied@redhat.com>
Cc: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: David Herrmann <dh.herrmann@gmail.com>
diff --git a/drivers/gpu/drm/drm_pci.c b/drivers/gpu/drm/drm_pci.c
index 5736aaa..f7af69b 100644
--- a/drivers/gpu/drm/drm_pci.c
+++ b/drivers/gpu/drm/drm_pci.c
@@ -468,8 +468,8 @@
 	} else {
 		list_for_each_entry_safe(dev, tmp, &driver->legacy_dev_list,
 					 legacy_dev_list) {
-			drm_put_dev(dev);
 			list_del(&dev->legacy_dev_list);
+			drm_put_dev(dev);
 		}
 	}
 	DRM_INFO("Module unloaded\n");