drm/virtio: align blob resources to page sizes

They trigger the BUG_ON() in drm_gem_private_object_init otherwise.

Signed-off-by: Chia-I Wu <olvaffe@gmail.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20201219031959.92932-1-olvaffe@gmail.com


Cc: Gurchetan Singh <gurchetansingh@chromium.org>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>