net: phylink: fix SGMII inband autoneg enable

When we are operating in SGMII inband mode, it implies that there is a
PHY connected, and the ethtool advertisement for autoneg applies to
the PHY, not the SGMII link. When in 1000base-X mode, then this applies
to the 802.3z link and needs to be applied to the PCS.

Fix this.
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Link: https://lore.kernel.org/r/E1o9Ng2-005Qbe-3H@rmk-PC.armlinux.org.ukSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/phy/phylink.c

@@ -3040,7 +3040,9 @@ int phylink_mii_c22_pcs_config(struct mdio_device *pcs, unsigned int mode,
 
 	/* Ensure ISOLATE bit is disabled */
 	if (mode == MLO_AN_INBAND &&
-	    linkmode_test_bit(ETHTOOL_LINK_MODE_Autoneg_BIT, advertising))
+	    (interface == PHY_INTERFACE_MODE_SGMII ||
+	     interface == PHY_INTERFACE_MODE_QSGMII ||
+	     linkmode_test_bit(ETHTOOL_LINK_MODE_Autoneg_BIT, advertising)))
 		bmcr = BMCR_ANENABLE;
 	else
 		bmcr = 0;