igb: do not force retry count to 1 on 82580 phy

This change resolves an issue seen in some configurations where the link
may drop to 100Mb/s even though the link itself supports 1000Mb/s.  The
issue was root caused to the fact that we were only trying the link once.
Now instead we will try up to 5 attempts on a faulty cable before
downshifting to 100Mb/s.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/igb/e1000_phy.c

@@ -457,15 +457,6 @@ s32 igb_copper_link_setup_82580(struct e1000_hw *hw)
 	phy_data |= I82580_CFG_ENABLE_DOWNSHIFT;
 
 	ret_val = phy->ops.write_reg(hw, I82580_CFG_REG, phy_data);
-	if (ret_val)
-		goto out;
-
-	/* Set number of link attempts before downshift */
-	ret_val = phy->ops.read_reg(hw, I82580_CTRL_REG, &phy_data);
-	if (ret_val)
-		goto out;
-	phy_data &= ~I82580_CTRL_DOWNSHIFT_MASK;
-	ret_val = phy->ops.write_reg(hw, I82580_CTRL_REG, phy_data);
 
 out:
 	return ret_val;