[wm8960] jack sensing broken: plugging or unplugging of the headphones has no effect

On most systems, plugging in headphones switches off the speakers and removing the headphones switches them on again. Somehow, this is not working for the wm8960 in the reform.

Attempted (but non-working) fix: !6

jack sensing works in 9front, so this is most definitely a software and not a hardware issue