drm/msm: correct NULL pointer dereference in context_init

Correct attempted NULL pointer dereference in context_init() when
running without an IOMMU.
Reviewed-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Brian Masney <masneyb@onstation.org>
Fixes: 295b22ae ("drm/msm: Pass the MMU domain index in struct msm_file_private")
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20190627020515.5660-1-masneyb@onstation.org

drivers/gpu/drm/msm/msm_drv.c

@@ -619,7 +619,7 @@ static int context_init(struct drm_device *dev, struct drm_file *file)
 
 	msm_submitqueue_init(dev, ctx);
 
-	ctx->aspace = priv->gpu->aspace;
+	ctx->aspace = priv->gpu ? priv->gpu->aspace : NULL;
 	file->driver_priv = ctx;
 
 	return 0;