drm/i915: Promote IS_BROADWELL to a simple macro

If we allow it a dedicated flag in dev_priv we enable the
compiler to nicely optimize conditions like IS_HASSWELL ||
IS_BROADWELL.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index d205b05..6d71709 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -735,6 +735,7 @@
 	func(is_valleyview) sep \
 	func(is_cherryview) sep \
 	func(is_haswell) sep \
+	func(is_broadwell) sep \
 	func(is_skylake) sep \
 	func(is_broxton) sep \
 	func(is_kabylake) sep \
@@ -2553,7 +2554,7 @@
 #define IS_VALLEYVIEW(dev)	(INTEL_INFO(dev)->is_valleyview)
 #define IS_CHERRYVIEW(dev)	(INTEL_INFO(dev)->is_cherryview)
 #define IS_HASWELL(dev)	(INTEL_INFO(dev)->is_haswell)
-#define IS_BROADWELL(dev)	(!INTEL_INFO(dev)->is_cherryview && IS_GEN8(dev))
+#define IS_BROADWELL(dev)	(INTEL_INFO(dev)->is_broadwell)
 #define IS_SKYLAKE(dev)	(INTEL_INFO(dev)->is_skylake)
 #define IS_BROXTON(dev)		(INTEL_INFO(dev)->is_broxton)
 #define IS_KABYLAKE(dev)	(INTEL_INFO(dev)->is_kabylake)