vxge: add missing flush of reset_task

Commit 6e07ebd8 (drivers/net: remove unnecessary
flush_scheduled_work() calls) incorrectly removed the flush call
without replacing it with the appropriate work specific operation.
Fix it by flushing vdev->reset_task explicitly.

Pointed out by Jon Mason.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Jon Mason <jon.mason@exar.com>
Acked-by: Jon Mason <jon.mason@exar.com>
Signed-off-by: David S. Miller <davem@davemloft.net>