drm/i915: Nuke pipe A quirk on i830M

Apparently it does more harm than good. Thomas Richter reports that
it helps his machine (Thinkpad X31) and there's another report from a
Fujitsu S6010. Also, we've nuked it on i845G already to make Chris'
machine happy.

Cc: Thomas Richter <richter@rus.uni-stuttgart.de>
References: http://mid.mail-archive.com/538C54E0.8090507@rus.uni-stuttgart.de


Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>