ipq40xx: add support for Aruba AP-303H

ipq40xx: add support for Aruba AP-303H

The Aruba AP-303H is the hospitality version of the Aruba AP-303 with a
POE-passthrough enabled ethernet switch instead of a sigle PHY.

Hardware
--------

SoC:   Qualcomm IPQ4029
RAM:   512M DDR3
FLASH: - 128MB SPI-NAND (Macronix)
       - 4MB SPI-NOR (Macronix MX25R3235F)
TPM:   Atmel AT97SC3203
BLE:   Texas Instruments CC2540T
       attached to ttyMSM1
ETH:   Qualcomm QCA8075
LED:   WiFi (amber / green)
       System (red / green /amber)
       PSE (green)
BTN:   Reset
USB:   USB 2.0

To connect to the serial console, you can solder to the labled pads next
to the USB port or use your Aruba supplied UARt adapter.

Do NOT plug a standard USB cable into the Console labled USB-port!
Aruba/HPE simply put UART on the micro-USB pins. You can solder yourself
an adapter cable:

VCC - NC
 D+ - TX
 D- - RX
GND - GND

The console setting in bootloader and OS is 9600 8N1. Voltage level is
3.3V.

To enable a full list of commands in the U-Boot "help" command, execute
the literal "diag" command.

Installation
------------

1. Get the OpenWrt initramfs image. Rename it to ipq40xx.ari and put it
   into the TFTP server root directory. Configure the TFTP server to
   be reachable at 192.168.1.75/24. Connect the machine running the TFTP
   server to the E0 (!) ethernet port of the access point, as it only
   tries to pull from the WAN port.

2. Connect to the serial console. Interrupt autobooting by pressing
   Enter when prompted.

3. Configure the bootargs and bootcmd for OpenWrt.
   $ setenv bootargs_openwrt "setenv bootargs console=ttyMSM0,9600n8"
   $ setenv nandboot_openwrt "run bootargs_openwrt; ubi part aos1;
     ubi read 0x85000000 kernel; set fdt_high 0x87000000;
     bootm 0x85000000"
   $ setenv ramboot_openwrt "run bootargs_openwrt;
     setenv ipaddr 192.168.1.105; setenv serverip 192.168.1.75;
     netget; set fdt_high 0x87000000; bootm"
   $ setenv bootcmd "run nandboot_openwrt"
   $ saveenv

4. Load OpenWrt into RAM:
   $ run ramboot_openwrt

5. After OpenWrt booted, transfer the OpenWrt sysupgrade image to the
   /tmp folder on the device. You will need to plug into E1-E3 ports of
   the access point to reach OpenWrt, as E0 is the WAN port of the
   device.

6. Flash OpenWrt:
   $ ubidetach -p /dev/mtd16
   $ ubiformat /dev/mtd16
   $ sysupgrade -n /tmp/openwrt-sysupgrade.bin

To go back to the stock firmware, simply reset the bootcmd in the
bootloader to the original value:

  $ setenv bootcmd "boot"
  $ saveenv

Signed-off-by: David Bauer <mail@david-bauer.net>