i40evf: remove flush_scheduled_work call in i40evf_remove

flush_schedule_work blocks until completion of all scheduled
work items in global work-queue. This can cause deadlock in some
cases. i40evf_remove() cleans up necessary work items with
cancel_delayed_work_sync and cancel_work_sync. This fix removes
flush_schedule_work call inside i40evf_remove().

Signed-off-by: Sudheer Mogilappagari <sudheer.mogilappagari@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>