ARM: dts: BCM5301X: Add basic DT for Linksys EA6500 V2

It is wireless home router based on BCM4708A0 with BCM4360 + BCM4331
wireless chipsets. The BCM4331 5GHz chip currently isn't supported only
due to missing compatible firmware.

Signed-off-by: Rene Kjellerup <rk.katana.steel@gmail.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>