i40e: fix build warnings

Fixes following build warnings :

drivers/net/ethernet/intel/i40e/i40e_main.c:7057:13: warning:
'i40e_sync_udp_filters_subtask' defined but not used [-Wunused-function]
drivers/net/ethernet/intel/i40e/i40e_main.c:8524:13: warning:
'i40e_add_vxlan_port' defined but not used [-Wunused-function]
drivers/net/ethernet/intel/i40e/i40e_main.c:8569:13: warning:
'i40e_del_vxlan_port' defined but not used [-Wunused-function]
drivers/net/ethernet/intel/i40e/i40e_main.c:8604:13: warning:
'i40e_add_geneve_port' defined but not used [-Wunused-function]
drivers/net/ethernet/intel/i40e/i40e_main.c:8651:13: warning:
'i40e_del_geneve_port' defined but not used [-Wunused-function]

Fixes: 6a899024 ("i40e: geneve tunnel offload support")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>