igb: Add i2c interface to igb.

Some of our adapters have sensors on them accessible via i2c and a private
interface.  This patch implements the kernel interface for i2c to those sensors.
Subsequent patches will provide functions to export that data.

Signed-off-by: Carolyn Wyborny <carolyn.wyborny@intel.com>
Tested-by: Jeff Pieper <jeffrey.e.pieper@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
diff --git a/drivers/net/ethernet/intel/igb/e1000_82575.c b/drivers/net/ethernet/intel/igb/e1000_82575.c
index fdaaf27..51e3f4f 100644
--- a/drivers/net/ethernet/intel/igb/e1000_82575.c
+++ b/drivers/net/ethernet/intel/igb/e1000_82575.c
@@ -33,6 +33,7 @@
 
 #include <linux/types.h>
 #include <linux/if_ether.h>
+#include <linux/i2c.h>
 
 #include "e1000_mac.h"
 #include "e1000_82575.h"
@@ -2314,6 +2315,8 @@
 	.acquire              = igb_acquire_phy_82575,
 	.get_cfg_done         = igb_get_cfg_done_82575,
 	.release              = igb_release_phy_82575,
+	.write_i2c_byte       = igb_write_i2c_byte,
+	.read_i2c_byte        = igb_read_i2c_byte,
 };
 
 static struct e1000_nvm_operations e1000_nvm_ops_82575 = {