bmips: add support for Actiontec R1000H

bmips: add support for Actiontec R1000H

The  Actiontec R1000H is a gigabit wifi router, 2.4 GHz single band with
two external antennas. It comes with a coaxial HomePNA port.

Hardware:
 - SoC: Broadcom BCM6368
 - CPU: dual core BMIPS4350 V3.1 @400Mhz
 - RAM: 64 MB DDR
 - Flash: 32 MB parallel NOR
 - LAN switch: Broadcom BCM53115, 5x 1Gbit
 - LAN coaxial : 1x HPNA 3.1, CG3211 + CG3213
 - Wifi 2.4 GHz: Broadcom BCM4322 802.11bgn
 - USB: 1x 2.0
 - Buttons: 2x, 1 reset
 - LEDs: 7x
 - UART: yes

The HPNA hardware probably needs a firmware to make the coaxial port work.
In the OEM firmware, it's apparently sent with an utility (inhpna) through
the ethernet port.

Installation via CFE web UI:
  1. Connect the UART serial port.
  2. Power on the router and press enter at the console prompt to stop the
     bootloader.
  4. Browse to http://192.168.1.1 and upload the OpenWrt CFE firmware
  5. Wait a few minutes for it to finish

Signed-off-by: Daniel González Cabanelas <dgcbueu@gmail.com>
(cherry picked from commit e1a55de7a7eafd40a4fab5f29153a1a3c3606818)