drm/i915 Add golden context support for Gen9

This patch includes the Gen9 batch buffer to generate
a 'golden context' for that product family.

Signed-off-by: Armin Reese <armin.c.reese@intel.com>
Reviewed-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>