ARM: mvebu: ensure the mdio node has a clock reference on Armada 38x

The mvmdio driver accesses some register of the Ethernet unit. It
therefore takes a reference and enables a clock. However, on Armada
38x, no clock specification was given in the Device Tree, which leads
the mvmdio driver to fail when being used as a module and loaded
before the mvneta driver: it tries to access a register from a
hardware unit that isn't clocked.
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Link: https://lkml.kernel.org/r/1395790439-21332-3-git-send-email-thomas.petazzoni@free-electrons.comAcked-by: Andrew Lunn <andrew@lunn.ch>
Acked-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>

arch/arm/boot/dts/armada-38x.dtsi

@@ -336,6 +336,7 @@ mdio {
 				#size-cells = <0>;
 				compatible = "marvell,orion-mdio";
 				reg = <0x72004 0x4>;
+				clocks = <&gateclk 4>;
 			};
 
 			coredivclk: clock@e4250 {