drm/i915/skl: Add an IS_GEN9() define

Reviewed-by: NThomas Wood <thomas.wood@intel.com>
Signed-off-by: NDamien Lespiau <damien.lespiau@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_drv.h

@@ -2123,6 +2123,7 @@ struct drm_i915_cmd_table {
 #define IS_GEN6(dev)	(INTEL_INFO(dev)->gen == 6)
 #define IS_GEN7(dev)	(INTEL_INFO(dev)->gen == 7)
 #define IS_GEN8(dev)	(INTEL_INFO(dev)->gen == 8)
+#define IS_GEN9(dev)	(INTEL_INFO(dev)->gen == 9)
 
 #define RENDER_RING		(1<<RCS)
 #define BSD_RING		(1<<VCS)