Initialise ctr_completion variable before use.

Cc: <stable@vger.kernel.org>
Signed-off-by: NHarsh Jain <harshjain.prof@gmail.com>
Signed-off-by: NStephan Mueller <smueller@chronox.de>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>