net: socionext: Demote non-compliant kernel-doc headers

Fixes the following W=1 kernel build warning(s):

 drivers/net/ethernet/socionext/sni_ave.c:28: warning: expecting prototype for sni_ave.c(). Prototype was for AVE_IDR() instead
Signed-off-by: Yang Shen <shenyang39@huawei.com>
Reviewed-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/socionext/sni_ave.c

 // SPDX-License-Identifier: GPL-2.0
-/**
+/*
  * sni_ave.c - Socionext UniPhier AVE ethernet driver
  * Copyright 2014 Panasonic Corporation
  * Copyright 2015-2017 Socionext Inc.