ramips: rt305x: add support for Edimax 3G-6200N

Support for Edimax 3G-6200N router with USB.

Signed-off-by: Lukasz Golebiowski <lgolebio@gmail.com>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@32682 3c298f89-4303-0410-b956-a3cf2f4a3e73
Added support for Edimax 3G-6200NL  & Pentagram P6367