ionic: unlock queue mutex in error path

On an error return, jump to the unlock at the end to be sure
to unlock the queue_lock mutex.

Fixes: 0925e9db

 ("ionic: use mutex to protect queue operations")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Shannon Nelson <snelson@pensando.io>
Signed-off-by: David S. Miller <davem@davemloft.net>