wifi: ath11k: fix sleeping-in-atomic in ath11k_mac_op_set_bitrate_mask()

wifi: ath11k: fix sleeping-in-atomic in ath11k_mac_op_set_bitrate_mask()

ath11k_mac_disable_peer_fixed_rate() is passed as the iterator to
ieee80211_iterate_stations_atomic(). Note in this case the iterator is
required to be atomic, however ath11k_mac_disable_peer_fixed_rate() does
not follow it as it might sleep. Consequently below warning is seen:

BUG: sleeping function called from invalid context at wmi.c:304
Call Trace:
 <TASK>
 dump_stack_lvl
 __might_resched.cold
 ath11k_wmi_cmd_send
 ath11k_wmi_set_peer_param
 ath11k_mac_disable_peer_fixed_rate
 ieee80211_iterate_stations_atomic
 ath11k_mac_op_set_bitrate_mask.cold

Change to ieee80211_iterate_stations_mtx() to fix this issue.

Tested-on: WCN6855 hw2.0 PCI WLAN.HSP.1.1-03125-QCAHSPSWPL_V1_V2_SILICONZ_LITE-3.6510.30

Fixes: d5c65159f289 ("ath11k: driver for Qualcomm IEEE 802.11ax devices")
Signed-off-by: Baochen Qiang <quic_bqiang@quicinc.com>
Link: https://patch.msgid.link/20250603-ath11k-use-non-atomic-iterator-v1-1-d75762068d56@quicinc.com
Signed-off-by: Jeff Johnson <jeff.johnson@oss.qualcomm.com>