wifi: ath11k: change complete() to complete_all() for scan.completed

Currently commit 1f682dc9 ("ath11k: reduce the wait time of 11d scan
and hw scan while add interface") introduced a wait_for_completion_timeout
operation for ar->scan.completed, another one is existed in ath11k_scan_stop(),
then ath11k has two places to wait for the ar->scan.completed and they
run in different thread, thus it is possible to happend that the two
thread both enter wait status. To handle this scenario, ath11k should
change the complete() to complete_all() for the ar->scan.completed. This
also work well when it is only one thread wait for ar->scan.completed.

Tested-on: WCN6855 hw2.0 PCI WLAN.HSP.1.1-03125-QCAHSPSWPL_V1_V2_SILICONZ_LITE-3

Signed-off-by: Wen Gong <quic_wgong@quicinc.com>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/20220919024413.25083-1-quic_wgong@quicinc.com