linux-phytec-fsl

drm/nouveau/drm: fix crash in vram manager debug callback

It's probably impossible to hit it now on mainline kernel.
I only noticed it because one of my debugging patches uses it.

Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>