ioat: fail self-test if wait_for_completion times out

wait_for_completion_timeout reaching timeout was being ignored,
fail the self-test if timeout condition occurs.

v2: fixup of coding style issues.

Signed-off-by: Nicholas Mc Guire <der.herr@hofr.at>
Acked-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Prarit Bhargava <prarit@redhat.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>