drm/nouveau/pm: prevent creating a perfctr object when signals are not found

Since a new class has been introduced to query signals, we can now
return an error when the userspace wants to monitor unknown signals.

Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
1 file changed