drm/i915: Fix product names and #defines

IGD* isn't a useful name.  Replace with the codenames, as sourced from
pci.ids.

Signed-off-by: Adam Jackson <ajax@redhat.com>
[anholt: Fixed up for merge with pineview/ironlake changes]
Signed-off-by: Eric Anholt <eric@anholt.net>
diff --git a/drivers/gpu/drm/i915/intel_overlay.c b/drivers/gpu/drm/i915/intel_overlay.c
index 49110b3..2639591 100644
--- a/drivers/gpu/drm/i915/intel_overlay.c
+++ b/drivers/gpu/drm/i915/intel_overlay.c
@@ -172,7 +172,7 @@
 #define OFC_UPDATE		0x1
 
 #define OVERLAY_NONPHYSICAL(dev) (IS_G33(dev) || IS_I965G(dev))
-#define OVERLAY_EXISTS(dev) (!IS_G4X(dev) && !IS_IGDNG(dev))
+#define OVERLAY_EXISTS(dev) (!IS_G4X(dev) && !IS_IRONLAKE(dev))
 
 
 static struct overlay_registers *intel_overlay_map_regs_atomic(struct intel_overlay *overlay)