apm821xx: add support for the Western Digital MyBook Live Series

apm821xx: add support for the Western Digital MyBook Live Series

Hardware Highlights:

This patch adds support for Western Digital MyBook Live Series:
CPU: AMCC PowerPC  UNKNOWN (PVR=12c41c83) at 800 MHz (PLB=200, OPB=100, EBC=100 MHz)
     32 kB I-Cache 32 kB D-Cache, 256 kB L2-Cache, 32 kB OnChip Memory
Board: Apollo-3G - APM82181 Board, 1*SATA
DRAM:  256 MB (2x NT5TU64M16GG-AC)
FLASH: 512 kB (SST 39VF040)
Ethernet: 1xRGMII - 1 Gbit - Broadcom PHY BCM54610

WARNING: The serial port needs a TTL/RS-232 v3.3 level converter!

The MyBook Live Duo additionally features a 1x USB 2.0 host port
and can support a second hard-drive.

This target produces two images for a target.
 1. ext4 image
    The extracted/raw image can be directly installed on
    the internal HDD via "dd if=img.ext4 of=/dev/sdX".

    This can either be done in place with the stock MyBook Live
    firmware via ssh. Or by removing the HDD and writing the image
    with a different PC.

    The the compressed images are useful for sysupgrade.

 2. recovery.tar image for TFTP and Serial.

    extract the recovery.tar to a TFTP server directory.

    On the MyBook Live (Duo) serial port - Hit Enter during u-boot and insert:
    # setenv serverip 192.168.1.254; setenv ipaddr 192.168.1.1; run net_self

    Where 192.168.1.254 is your TFTP server.

Signed-off-by: Christian Lamparter <chunkeey@gmail.com>