i40e: disable NAPI right after disabling irqs when handling xsk_pool

Disable NAPI before shutting down queues that this particular NAPI
contains so that the order of actions in i40e_queue_pair_disable()
mirrors what we do in i40e_queue_pair_enable().

Fixes: 123cecd4

 ("i40e: added queue pair disable/enable functions")
Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Tested-by: Chandan Kumar Rout <chandanx.rout@intel.com> (A Contingent Worker at Intel)
Acked-by: Magnus Karlsson <magnus.karlsson@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>