drm/i915: Enable GMBUS for post-gen2 chipsets

With the recent SDVO fix, this is working on all the machines I have to
hand - except for an 845G.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>

drivers/gpu/drm/i915/intel_i2c.c

@@ -384,7 +384,8 @@ int intel_setup_gmbus(struct drm_device *dev)
 		bus->reg0 = i | GMBUS_RATE_100KHZ;
 
 		/* XXX force bit banging until GMBUS is fully debugged */
-		bus->force_bit = intel_gpio_create(dev_priv, i);
+		if (IS_GEN2(dev))
+			bus->force_bit = intel_gpio_create(dev_priv, i);
 	}
 
 	intel_i2c_reset(dev_priv->dev);