ARM: dts: orion5x: convert ls-chl to FDT

This patch converts my orion5x ls-chl Linkstation device to device tree.

[gregory.clement@free-electrons.com: fix title, add back the commit log,
move the removal of the platform in an other patch]
Signed-off-by: Ashley Hughes <ashley.hughes@blueyonder.co.uk>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>