i40e: verify string count matches even on early return

Similar to i40e_get_ethtool_stats, add a goto to verify that the data
pointer for the strings lines up with the expected stats count. This
helps ensure that bugs are not introduced when adding stats.
Signed-off-by: NJacob Keller <jacob.e.keller@intel.com>
Tested-by: NAndrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>

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

@@ -2342,7 +2342,7 @@ static void i40e_get_stat_strings(struct net_device *netdev, u8 *data)
 	}
 
 	if (vsi != pf->vsi[pf->lan_vsi] || pf->hw.partition_id != 1)
-		return;
+		goto check_data_pointer;
 
 	i40e_add_stat_strings(&data, i40e_gstrings_veb_stats);
 
@@ -2354,6 +2354,7 @@ static void i40e_get_stat_strings(struct net_device *netdev, u8 *data)
 	for (i = 0; i < I40E_MAX_USER_PRIORITY; i++)
 		i40e_add_stat_strings(&data, i40e_gstrings_pfc_stats, i);
 
+check_data_pointer:
 	WARN_ONCE(data - p != i40e_get_stats_count(netdev) * ETH_GSTRING_LEN,
 		  "stat strings count mismatch!");
 }