mpc85xx: add support for Enterasys WS-AP3710i

mpc85xx: add support for Enterasys WS-AP3710i

Hardware
--------

SoC:   NXP P1020 (2x e500 @ 800MHz)
RAM:   256M DDR3 (Micron)
FLASH: 32M NOR (Spansion S29GL128S)
BTN:   1x Reset
WiFi:  1x Atheros AR9590 2.4 bgn 3x3
       2x Atheros AR9590 5.0 an 3x3
ETH:   1x Gigabit Ethernet (Atheros AR8033)
LED:   System (green/red) - Radio{0,1} (green)
       LAN (connected to PHY)
        - GE blue
        - FE green

Serial is a Cisco-compatible RJ45 next to the ethernet port.
115200-N-8 are the settings for OS and U-Boot.

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

1. Grab the OpenWrt initramfs, rename it to 01C8A8C0.img. Place it in
   the root directory of a TFTP server and serve it at
   192.168.200.200/24.

2. Connect to the serial port and boot the AP. Stop autoboot in U-Boot
   by pressing Enter when prompted. Credentials are identical to the one
   in the APs interface. By default it is admin / new2day.

3. Set the bootcmd so the AP can boot OpenWrt by executing

   $ setenv boot_openwrt "setenv bootargs;
     cp.b 0xee000000 0x1000000 0x1000000; bootm 0x1000000"
   $ setenv bootcmd "run boot_openwrt"
   $ saveenv

   If you plan on going back to the vendor firmware - the bootcmd for it
   is stored in the boot_flash variable.

4. Load the initramfs image to RAM and boot by executing

   $ tftpboot 0x1000000 192.168.200.200:01C8A8C0.img; bootm

5. Make a backup of the "firmware" partition if you ever wish to go back
   to the vendor firmware.

6. Upload the OpenWrt sysupgrade image via SCP to the devices /tmp
   folder.

7. Flash OpenWrt using sysupgrade.

   $ sysupgrade -n /tmp/openwrt-sysupgrade.bin

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