ath10k: fix patching mistake for AP/IBSS CSA

Mistakenly v1 of `ath10k: fix AP/IBSS CSA with
template based fw`
(81a9a17d) was
applied.

This patch applies the missing bits from v2:
 * remove unnecessary locking
 * add some (sanity) checks

There are no practical functionality differences
between v1 and v2.

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>