drm/i915: Fix use after free when printing load failure

Commit d15d7538 ("drm/i915: Tune down init error message due
to failure injection") added i915_load_error message to failure
path on device initialization. The message is printed
after the device is freed. And as the message printing helper
uses the device structure, this leads to use after free.

Spotted by Kasan.

Cc: Imre Deak <imre.deak@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1458721906-10625-1-git-send-email-mika.kuoppala@intel.com

drivers/gpu/drm/i915/i915_dma.c

@@ -1398,10 +1398,10 @@ int i915_driver_load(struct drm_device *dev, unsigned long flags)
 	intel_runtime_pm_put(dev_priv);
 	i915_driver_cleanup_early(dev_priv);
 out_free_priv:
-	kfree(dev_priv);
-
 	i915_load_error(dev_priv, "Device initialization failed (%d)\n", ret);
 
+	kfree(dev_priv);
+
 	return ret;
 }