MIPS: Jz4740: Add qi_lb60 board support

MIPS: Jz4740: Add qi_lb60 board support

Add support for the qi_lb60 (a.k.a QI Ben NanoNote) clamshell device
from Qi hardware:

http://en.qi-hardware.com/wiki/Ben_NanoNote
http://en.qi-hardware.com/wiki/Main_Page
http://en.wikipedia.org/wiki/Qi_hardware

This Jz4740-based clamshell device does not use NOR flash to boot.
The initial bring-up assumes that U-Boot is directly loaded into SDRAM
using USB boot tool, and starts from 0x80100000.

About USB boot tool
-------------------

Jz4740 is one of the XBurst processors with USB boot functionality
supported.  The CPU can boot from a small ROM in the LSI, initialize
CPU and USB module, then wait for USB commands from the USB host.
We can send 8 KB binary data to the CPU cache using USB boot tool.

USB boot tool is available to the public at Ingenic website.  Also
there is an alternative Debian package named xburst-tools.

Signed-off-by: Xiangfu Liu <xiangfu@openmobilefree.net>
Acked-by: Daniel <zpxu@ingenic.cn>
Signed-off-by: Shinya Kuribayashi <skuribay@pobox.com>