ixgbe: implement SFF diagnostic monitoring via ethtool

This patch adds support for reading data from SFP+ modules over i2c.

Signed-off-by: Aurélien Guillaume <footplus@gmail.com>
Signed-off-by: Emil Tantilov <emil.s.tantilov@intel.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe.h b/drivers/net/ethernet/intel/ixgbe/ixgbe.h
index b91f9b6..196002b 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe.h
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe.h
@@ -620,6 +620,7 @@
 	__IXGBE_DOWN,
 	__IXGBE_SERVICE_SCHED,
 	__IXGBE_IN_SFP_INIT,
+	__IXGBE_READ_I2C,
 };
 
 struct ixgbe_cb {