iavf: fix double unlock of crit_lock

The crit_lock mutex could be unlocked twice as reported here
https://lists.osuosl.org/pipermail/intel-wired-lan/Week-of-Mon-20210823/025525.html

Remove the superfluous unlock. Technically the problem was already
present before 5ac49f3c as that commit only replaced the locking
primitive, but no functional change.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Fixes: 5ac49f3c ("iavf: use mutexes for locking of critical sections")
Fixes: bac84861 ("iavf: Refactor the watchdog state machine")
Signed-off-by: Stefan Assmann <sassmann@kpanic.de>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

drivers/net/ethernet/intel/iavf/iavf_main.c

@@ -1965,7 +1965,6 @@ static void iavf_watchdog_task(struct work_struct *work)
 		}
 		adapter->aq_required = 0;
 		adapter->current_op = VIRTCHNL_OP_UNKNOWN;
-		mutex_unlock(&adapter->crit_lock);
 		queue_delayed_work(iavf_wq,
 				   &adapter->watchdog_task,
 				   msecs_to_jiffies(10));