drm/nouveau/kms/nv04: use vzalloc for nv04_display

The struct is giant, and triggers an order-7 allocation (512K). There is
no reason for this to be kmalloc-type memory, so switch to vmalloc. This
should help loading nouveau on low-memory and/or long-running systems.

Reported-by: Nathan E. Egge <unlord@xiph.org>
Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
Cc: stable@vger.kernel.org
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Reviewed-by: Karol Herbst <kherbst@redhat.com>
Signed-off-by: Karol Herbst <kherbst@redhat.com>
Link: https://gitlab.freedesktop.org/drm/nouveau/-/merge_requests/10