ramips: Add base-files for HiWiFi HC5x61 models

HiWiFi HC5661/5761/5861 models are manufactured by http://www.hiwifi.com

. These models have similar hardware specs(MT7620A + 128M DDR2 + 16M flash). This patch adds support for them.

The original author is Justin Liu (rssnsj@gmail.com). I ported the patch to trunk and submitted it here with his approval.

v3 fix
   1: Fixed model order
   2: Remove manufacturer name from model name
   3: Use a hacky but prettier way to get mac address.

Signed-off-by: Xiaoning Kang <kangxn@163.com>

SVN-Revision: 47111