ARM: dts: add buffalo linkstation ls-wxl/wsxl

Add dts file to support Buffalo Linkstation LS-WXL and LS-WSXL,
which are 2-bay NAS with 3.5" and 2.5" HDD respectively.

Signed-off-by: Roger Shimizu <rogershimizu@gmail.com>
Reviewed-by: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
Acked-by: Andrew Lunn <andrew@lunn.ch>
Acked-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>