ralink: fixes mpr a1/a2 network setup

Signed-off-by: Suschman <suschman@gmx.net>
Signed-off-by: John Crispin <blogic@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@38348 3c298f89-4303-0410-b956-a3cf2f4a3e73