be2net: Use cancel_delayed_work_sync instead of cancel_delayed_work()

Use cancel_delayed_work_sycn instead of cancel_delayed_work() to reliably kill be_worker() as it rearms itself.

Signed-off-by: Sathya Perla <sathyap@serverengines.com>
Signed-off-by: David S. Miller <davem@davemloft.net>