ath11k: avoid unnecessary BH disable lock in STA kickout event

In STA kickout event processing, the peer object is protected
under spin lock BH. Release this lock after picking up the vdev_id
from the peer object instead after ieee80211_report_low_ack().
This will minimize the lock hold period which will improve
performance since base_lock is used across the data path.
This was found in code review.

Tested-on: IPQ8074 hw2.0 AHB WLAN.HK.2.5.0.1-00729-QCAHKSWPL_SILICONZ-3 v2

Signed-off-by: Karthikeyan Periyasamy <quic_periyasa@quicinc.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/1636560388-24955-1-git-send-email-quic_periyasa@quicinc.com