ath10k: fix locking for WEP keys

peer->keys needs to be protected by data_lock
since it is also accessed from the WMI path.

Both install() and clear() routines for peer
keys modify the key contents, so use the data_lock
to avoid races.

Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>