ARM: mvebu: add Device Tree description of the EHCI controller on Armada 38x

The Marvell Armada 38x SoCs contains one EHCI controller. This commit
adds the Device Tree description of this interface at the SoC level,
and also enables the USB2 port on the Armada 385 DB platform.

Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Link: https://lkml.kernel.org/r/1400149062-32661-16-git-send-email-gregory.clement@free-electrons.com


Signed-off-by: Jason Cooper <jason@lakedaemon.net>