iavf: add iavf_schedule_aq_request() helper

Add helper for set iavf aq request AVF_FLAG_AQ_* and immediately
schedule watchdog_task. Helper will be used in cases where it is
necessary to run aq requests asap

Signed-off-by: Petr Oros <poros@redhat.com>
Co-developed-by: Michal Schmidt <mschmidt@redhat.com>
Signed-off-by: Michal Schmidt <mschmidt@redhat.com>
Co-developed-by: Ivan Vecera <ivecera@redhat.com>
Signed-off-by: Ivan Vecera <ivecera@redhat.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Tested-by: Rafal Romanowski <rafal.romanowski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>