drm/i915: add missing gen2 pipe A quirk entries

For some odd reason we've missed i830 and a i855 variant. Also
kill the two now redundant i830 entries.

v2: Don't add the missing 855 id to the pipe A quirk list, we seem to
lack justification for it.

Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>