drm/i915: ivb: fix edp voltage swing reg val
drm/i915: ivb: fix edp voltage swing reg val

From Imre Deak
0c08a4e4ed1f4441a1554e93b3202477997dc73a in ubuntu 3.8
77fa4cbd5fa389e28419bbe8ac491b5fdd54840d in mainline linux

orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars