drm/i915: Replace "INTEL_INFO->gen == x" checks with IS_GENx

This way optimization from a previous patch works even better.

v2: Rebase.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 6d71709..f33b2e6 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2702,7 +2702,7 @@
 				 IS_CHERRYVIEW(dev) || IS_SKYLAKE(dev) || \
 				 IS_KABYLAKE(dev) || IS_BROXTON(dev))
 #define HAS_RC6(dev)		(INTEL_INFO(dev)->gen >= 6)
-#define HAS_RC6p(dev)		(INTEL_INFO(dev)->gen == 6 || IS_IVYBRIDGE(dev))
+#define HAS_RC6p(dev)		(IS_GEN6(dev) || IS_IVYBRIDGE(dev))
 
 #define HAS_CSR(dev)	(IS_GEN9(dev))