hostap: convert to struct proc_ops

commit 97a32539 ("proc: convert everything to "struct proc_ops"")
forget do this convering for prism2_download_aux_dump_proc_fops.

Fixes: 97a32539 ("proc: convert everything to "struct proc_ops"")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20200326032432.20384-1-yuehaibing@huawei.com