ixgbe: Use MDIO_PRTAD_NONE consistently

The value MDIO_PRTAD_NONE should be used to indicate no PHY address.
Not 0, not 0xFFFF. Use the MDIO_PRTAD_NONE value consistently.
Signed-off-by: Mark Rustad <mark.d.rustad@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

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

@@ -346,8 +346,8 @@ s32 ixgbe_identify_phy_generic(struct ixgbe_hw *hw)
 				return 0;
 			}
 		}
-		/* clear value if nothing found */
-		hw->phy.mdio.prtad = 0;
+		/* indicate no PHY found */
+		hw->phy.mdio.prtad = MDIO_PRTAD_NONE;
 		return IXGBE_ERR_PHY_ADDR_INVALID;
 	}
 	return 0;

drivers/net/ethernet/intel/ixgbe/ixgbe_x550.c

@@ -1459,7 +1459,7 @@ ixgbe_setup_mac_link_sfp_x550a(struct ixgbe_hw *hw, ixgbe_link_speed speed,
 	/* Configure internal PHY for KR/KX. */
 	ixgbe_setup_kr_speed_x550em(hw, speed);
 
-	if (!hw->phy.mdio.prtad || hw->phy.mdio.prtad == 0xFFFF)
+	if (hw->phy.mdio.prtad == MDIO_PRTAD_NONE)
 		return IXGBE_ERR_PHY_ADDR_INVALID;
 
 	/* Get external PHY device id */