bmips: add support for Observa VH4032N

bmips: add support for Observa VH4032N

The Observa VH4032N is an xDSL wifi router with a vertical white casing
and two internal antennas connected via UFL.

Hardware:
 - SoC: Broadcom BCM6368
 - CPU: dual core BMIPS4350 V3.1 @400MHz
 - RAM: 128 MB DDR
 - Flash: 32 MB parallel NOR
 - Ethernet LAN: 4x 100Mbit
 - Wifi 2.4/5 GHz: onboard Broadcom BCM43222 802.11abgn
 - USB: 3x 2.0
 - Buttons: 2x, 1 reset
 - LEDs: 8x, blue and red
 - UART: 1x

Installation via OEM web UI:
  1. Use the admin credentials to login via web UI
  2. Go to Managament->Update firmware and select the OpenWrt CFE firmware
  3. Press "Update Firmware" button and wait some minutes until it finish

Signed-off-by: Daniel González Cabanelas <dgcbueu@gmail.com>