staging: omapdrm/omap_gem_dmabuf.c: fix memory leakage

There is a memory leakage in variable sg if it goes to error.
Signed-off-by: Cong Ding <dinggnu@gmail.com>
Signed-off-by: Rob Clark <rob@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/omapdrm/omap_gem_dmabuf.c

@@ -53,10 +53,10 @@ static struct sg_table *omap_gem_map_dma_buf(
 	/* this should be after _get_paddr() to ensure we have pages attached */
 	omap_gem_dma_sync(obj, dir);
 
+	return sg;
 out:
-	if (ret)
+	kfree(sg);
 	return ERR_PTR(ret);
-	return sg;
 }
 
 static void omap_gem_unmap_dma_buf(struct dma_buf_attachment *attachment,