ralink: various fixes to the wm8960 setup code

still no sound but the codec is properly detected now, powers up and i can hear
noise on the speakers.

Signed-off-by: John Crispin <blogic@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@43305 3c298f89-4303-0410-b956-a3cf2f4a3e73