i40e: spelling error

Fix a spelling error, s/extention/extension/.

Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Tested-by: Kavindya Deegala <kavindya.s.deegala@intel.com>
Signed-off-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --cc drivers/net/ethernet/intel/i40e/i40e_txrx.c
Simple merge

diff --cc drivers/net/ethernet/intel/i40evf/i40e_txrx.c
Simple merge