mac80211: ath11k: fix broadcast failures during GTK rekeying

mac80211: ath11k: fix broadcast failures during GTK rekeying

Revert key_cipher change to NONE when clearing key.
Setting to NONE triggers asserts in the firmware and causes broadcast
drops with ath11k firmware 2.9.0.1, so until a future blob
fixes this, revert this as a workaround.

Imported from
https://git.codelinaro.org/clo/qsdk/oss/system/feeds/wlan-open/-/blob/win.wlan_host_opensource.3.0.r24/patches/ath11k/350-ath11k-Revert-clear-the-keys-properly-when-DISABLE_K.patch

Related discussion links:

- https://github.com/openwrt/openwrt/issues/9555
- https://lore.kernel.org/linux-wireless/Z2Q9POuV-6MIdzRf@pilgrim/T/#t

Signed-off-by: Henry Tung <henryptung@gmail.com>
Link: https://github.com/openwrt/openwrt/pull/18705
Signed-off-by: Robert Marko <robimarko@gmail.com>