iavf: use iavf_schedule_aq_request() helper

Use the iavf_schedule_aq_request() helper when we need to
schedule a watchdog task immediately. No functional change.

Signed-off-by: Petr Oros <poros@redhat.com>
Reviewed-by: Wojciech Drewek <wojciech.drewek@intel.com>
Tested-by: Rafal Romanowski <rafal.romanowski@intel.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>