ath9k: Clear key cache explicitly on disabling hardware

stable inclusion
from linux-4.19.205
commit d2fd9d34210f34cd0ff5b33fa94e9fcc2a513cea
CVE: CVE-2020-3702

--------------------------------

commit 73488cb2 upstream.

Now that ath/key.c may not be explicitly clearing keys from the key
cache, clear all key cache entries when disabling hardware to make sure
no keys are left behind beyond this point.

Signed-off-by: Jouni Malinen <jouni@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20201214172118.18100-3-jouni@codeaurora.org


Cc: Pali Rohár <pali@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Reviewed-by: Xiu Jianfeng <xiujianfeng@huawei.com>
Reviewed-by: Yue Haibing <yuehaibing@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>