i40e: display priority_xon and priority_xoff stats

Display some more stats that were already being counted, to help users
understand when priority xon/xoff packets are being sent/received

Signed-off-by: Alice Michael <alice.michael@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/i40e/i40e_ethtool.c

@@ -126,6 +126,10 @@ static const struct i40e_stats i40e_gstrings_stats[] = {
 	I40E_PF_STAT("link_xoff_rx", stats.link_xoff_rx),
 	I40E_PF_STAT("link_xon_tx", stats.link_xon_tx),
 	I40E_PF_STAT("link_xoff_tx", stats.link_xoff_tx),
+	I40E_PF_STAT("priority_xon_rx", stats.priority_xon_rx),
+	I40E_PF_STAT("priority_xoff_rx", stats.priority_xoff_rx),
+	I40E_PF_STAT("priority_xon_tx", stats.priority_xon_tx),
+	I40E_PF_STAT("priority_xoff_tx", stats.priority_xoff_tx),
 	I40E_PF_STAT("rx_size_64", stats.rx_size_64),
 	I40E_PF_STAT("rx_size_127", stats.rx_size_127),
 	I40E_PF_STAT("rx_size_255", stats.rx_size_255),