ARM: dts: Hurricane 2: Add basic support for Ubiquiti UniFi Switch 8

Add basic board support for the Ubiquiti UniFi Switch 8 port model. This
is a small home and office use managed switch based on the BCM53342
switching control SoC.

Acked-by: Jon Mason <jon.mason@broadcom.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>