drm/i915: Don't return error on sink crc stop.

If we got to the point where we are trying to stop sink CRC
the main output of this function was already gotten properly,
so don't return the error and let userspace use the crc data.

Let's replace the errnos returns with some log messages.

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>