i40e: Add vsi.tx_restart to i40e ethtool stats

Add vsi.tx_restart to the i40e driver ethtool statistics

Signed-off-by: Nabil S. Alramli <dev@nalramli.com>
Tested-by: Gurucharan <gurucharanx.g@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>