ipq40xx: add support for Linksys WHW03 V1

ipq40xx: add support for Linksys WHW03 V1

Hardware:
=========
SOC:             Qualcomm IPQ4019
WiFi 1:          QCA4019 IEEE 802.11b/g/n
WiFi 2:          QCA4019 IEEE 802.11a/n/ac
WiFi 3:          QCA9886 IEEE 802.11a/n/ac
Bluetooth:       Qualcomm CSR8510 (A10)
Zigbee:          Silicon Labs EM3581 NCP + Skyworks SE2432L
Ethernet:        Qualcomm Atheros QCA8072 (2-port)
Flash:           Samsung KLM4G1FEPD (4GB eMMC)
RAM (NAND):      512MB
LED Controller:  NXP PCA9633 (I2C)
Buttons:         Single reset button (GPIO).

Ethernet:
=========
The device has 2 ethernet ports, configured as follows by default:
- left port: WAN
- right port: LAN

Wifi:
=====
The Wifi radios are turned off by default. To configure the router,
you will need to connect your computer to the LAN port of the device.

Bluetooth and Zigbee:
=====================
Configuration included but not tested.

Storage:
========
For compatibility with stock firmware, all of OpenWrt runs in a 136 MiB
eMMC partition (of which there are two copies, see below). You can also
use partition /dev/mmcblk0p19 "syscfg" (3.4 GiB) any way you see fit.
During very limited tests, stock firmware did not mount this partition.
However, backing up its stock content before use is recommended anyway.

Firmware:
=========
The device uses a dual firmware mechanism: it automatically reverts to
the previous firmware after 3 failed boot attempts.

You can switch to the inactive firmware copy by changing the "boot_part"
U-Boot environment variable. You can also do it by turning on the device
for a couple of seconds and then back off, 3 times in a row.

Installation:
=============
OpenWrt's "factory" image can be installed via the stock web UI:
1. Login to the UI. (The default password is printed on the label.)
2. Enter support mode by clicking on the "CA" link at the bottom.
3. Click "Connectivity", "Choose file", "Start", and ignore warnings.

This port is based on work done by flipy (https://github.com/flipy).

Signed-off-by: Rodrigo Balerdi <lanchon@gmail.com>
Link: https://github.com/openwrt/openwrt/pull/15345
Signed-off-by: Robert Marko <robimarko@gmail.com>