drm/i915: Support flags in whitlist WAs

Newer hardware adds flags to the whitelist work-around register. These
allow per access direction privileges and ranges.

Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Signed-off-by: Robert M. Fosha <robert.m.fosha@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190618010108.27499-2-John.C.Harrison@Intel.com