ice: Refactor a few Tx scheduler functions

The following functions were refactored to call a new common function,
ice_aqc_send_sched_elem_cmd():

- ice_aq_add_sched_elems()
- ice_aq_delete_sched_elems()
- ice_aq_move_sched_elems()
- ice_aq_query_sched_elems()
- ice_aq_cfg_sched_elems()
- ice_aq_suspend_sched_elems()
- ice_aq_resume_sched_elems()

Signed-off-by: Greg Priest <greg.priest@intel.com>
Signed-off-by: Anirudh Venkataramanan <anirudh.venkataramanan@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>