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_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index d2195c7..8439867 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1981,7 +1981,7 @@
 		return size;
 
 	/* Previous chips need a power-of-two fence region when tiling */
-	if (INTEL_INFO(dev)->gen == 3)
+	if (IS_GEN3(dev))
 		gtt_size = 1024*1024;
 	else
 		gtt_size = 512*1024;