drm/i915: Remove pipe A quirk remnants

With 830 the only thing needing pipe quirks, we can just drop the quirk
defines and replace the checks with IS_I830() checks.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170601143619.27840-8-ville.syrjala@linux.intel.com


Acked-by: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>