ar71xx: Buffalo WHR-HP-G300N kernel support

The initial support for the Buffalo WHR-HP-G300N box.
The code was confirmed to boot and run, but not tested in depth.

Known problem: iw phy phy0 info shows:
	Coverage class: 0 (up to 0m)
	Available Antennas: TX 0 RX 0

Signed-off-by: Yoichi Shinoda <shinoda@jaist.ac.jp>

SVN-Revision: 28567