drm/i915: Verify page layout for rotated VMA

Exercise creating rotated VMA and checking the page order within.

v2..v3: Be more creative in rotated params

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170213171558.20942-36-chris@chris-wilson.co.uk