ramips: Add support for Microduino MicroWRT

ramips: Add support for Microduino MicroWRT

MicroWRT is an wireless router with 2 USB,1 ethernet port. It
has a 16M flash and 64M DDR2 RAM. You can use most interface, such as
i2c, SPI, i2s and PCIe. Besides that there are three expansion borad to
combine with the core board. The detailed information, please refer to
https://www.microduino.cc/wiki/index.php?title=Main_Page

This patch adds support for it.
Because there is only one port,so disabled VLAN and use eth0 as lan
port. and only a power LED control by power pin.

Signed-off-by: 盛凯 <shengkai81@gmail.com>
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@45331 3c298f89-4303-0410-b956-a3cf2f4a3e73