i40e: Move function calls to i40e_shutdown instead of i40e_suspend

We should be stopping the service task and flow director on
shutdown not on suspension.

Signed-off-by: Catherine Sullivan <catherine.sullivan@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>