ARM: dts: Add basic devicetree for D-Link DNS-313

This adds a basic device tree for the D-Link DNS-313
NAS enclosure. This device has a thermal sensor and a
fan so we add a thermal zone for the chassis in the
device tree based on information from the product.

Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>