iavf: fix double unlock of crit_lock

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 3e0a61a5b57d as that commit only replaced the locking
primitive, but no functional change.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Fixes: 3e0a61a5b57d ("iavf: use mutexes for locking of critical sections")
Fixes: 174bee62d924 ("iavf: Refactor the watchdog state machine")
Signed-off-by: Stefan Assmann <sassmann@kpanic.de>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>