ARM: mvebu: add user LED support of Armada 370 RD

The Armada 370 RD has a GPIO controlled LED connected on MPP32, so
this commit adds the relevant hardware description to Armada 370 RD
Device Tree.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Acked-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lkml.kernel.org/r/1410429419-29820-3-git-send-email-thomas.petazzoni@free-electrons.com


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