drm/nouveau/secboot: set default error value in error register

Set a default error value in the mailbox 0 register so we can catch
cases where the secure boot binary fails early without being able to
report anything.

Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
1 file changed