ixgbe: send MFLCN to ethtool

MFLCN register is used to set Rx flow control on parts newer than 82598.

This patch sends the value of MFLCN to ethtool, so it can be used in a
register dump (ethtool -d).
Signed-off-by: Emil Tantilov <emil.s.tantilov@intel.com>
Tested-by: Stephen Ko <stephen.s.ko@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/ixgbe/ixgbe_ethtool.c

@@ -460,7 +460,7 @@ static void ixgbe_set_msglevel(struct net_device *netdev, u32 data)
 
 static int ixgbe_get_regs_len(struct net_device *netdev)
 {
-#define IXGBE_REGS_LEN  1128
+#define IXGBE_REGS_LEN  1129
 	return IXGBE_REGS_LEN * sizeof(u32);
 }
 
@@ -771,6 +771,9 @@ static void ixgbe_get_regs(struct net_device *netdev,
 	regs_buff[1125] = IXGBE_READ_REG(hw, IXGBE_PCIEECCCTL);
 	regs_buff[1126] = IXGBE_READ_REG(hw, IXGBE_PBTXECC);
 	regs_buff[1127] = IXGBE_READ_REG(hw, IXGBE_PBRXECC);
+
+	/* 82599 X540 specific registers  */
+	regs_buff[1128] = IXGBE_READ_REG(hw, IXGBE_MFLCN);
 }
 
 static int ixgbe_get_eeprom_len(struct net_device *netdev)