ARM: dts: BCM5301X: Add DT for WZR-1166DHP,DHP2

Buffalo WZR-1166DHP/WZR-1166DHP2  wireless router with

    - BCM4708A0
    - 128MiB NAND flash
    - 2T2R 11ac/a/b/g/n Wi-Fi
    - 4x 10/100/1000M ethernet switch
    - 1x USB 3.0 port

  WZR-1166DHP and WZR-1166DHP2 have different memory capacity.

  WZR-1166DHP
    - 512 MiB DDR2 SDRAM

  WZR-1166DHP2
    - 256 MiB DDR2 SDRAM

  These hardware components are very similar to the WZR-1750DHP
   except for the number of antennas.

Signed-off-by: SHIMAMOTO Takayoshi <takayoshi.shimamoto.360@gmail.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>