ARM: mvebu: use qsgmii phy-mode for Armada XP GP interfaces

The Armada XP GP isn't using rgmii-id connections between the MAC and
PHY, but instead a single QSGMII connection, which is a quad-SGMII
connection: a double pair of differential lines that are multiplexed
to convey the traffic of four network interfaces between a MAC and a
PHY.

Until now, the Armada XP GP was relying on the bootloader setting the
correct values in various configuration registers. With this change,
the mvneta driver can be used as a module on this platform.
Signed-off-by: NThomas Petazzoni <thomas.petazzoni@free-electrons.com>
Link: https://lkml.kernel.org/r/1397569821-5530-4-git-send-email-thomas.petazzoni@free-electrons.comTested-by: NArnaud Ebalard <arno@natisbad.org>
Tested-by: NWilly Tarreau <w@1wt.eu>
Signed-off-by: NJason Cooper <jason@lakedaemon.net>

arch/arm/boot/dts/armada-xp-gp.dts

@@ -146,22 +146,22 @@
 			ethernet@70000 {
 				status = "okay";
 				phy = <&phy0>;
-				phy-mode = "rgmii-id";
+				phy-mode = "qsgmii";
 			};
 			ethernet@74000 {
 				status = "okay";
 				phy = <&phy1>;
-				phy-mode = "rgmii-id";
+				phy-mode = "qsgmii";
 			};
 			ethernet@30000 {
 				status = "okay";
 				phy = <&phy2>;
-				phy-mode = "rgmii-id";
+				phy-mode = "qsgmii";
 			};
 			ethernet@34000 {
 				status = "okay";
 				phy = <&phy3>;
-				phy-mode = "rgmii-id";
+				phy-mode = "qsgmii";
 			};
 
 			/* Front-side USB slot */