drm/i915: Try to stop sink crc calculation on error.

Right now if we face any kind of error sink crc calculation
stays enabled.

So, let's give a shot and try to stop it anyway if it got enabled.

Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Rafael Antognolli <rafael.antognolli@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>