ARM: dts: orion5x: add buffalo linkstation ls-wtgl

Add dts file to support Buffalo Linkstation LS-WTGL,
which is marvell orion5x based 2-bay 3.5" HDD NAS.
Product info:
 - (JPN) http://buffalo.jp/products/catalog/storage/ls-wtgl_r1/
 - (ENG) http://www.buffalotech.com/support-and-downloads/download/LinkStation_Pro_Duo_Manual_web.pdf



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