wifi: ath11k: move locking outside of ath11k_mac_get_fw_stats()

wifi: ath11k: move locking outside of ath11k_mac_get_fw_stats()

Currently ath11k_mac_get_fw_stats() is acquiring/releasing ar->conf_mutex by itself.
In order to reuse this function in a context where that lock is already taken, move
lock handling to its callers, then the function itself only has to assert it.

There is only one caller now, i.e., ath11k_mac_op_sta_statistics(), so add lock handling
there.

Tested-on: WCN6855 hw2.0 PCI WLAN.HSP.1.1-03125-QCAHSPSWPL_V1_V2_SILICONZ_LITE-3.6510.37

Signed-off-by: Baochen Qiang <quic_bqiang@quicinc.com>
Reviewed-by: Vasanthakumar Thiagarajan <vasanthakumar.thiagarajan@oss.qualcomm.com>
Link: https://patch.msgid.link/20250220082448.31039-7-quic_bqiang@quicinc.com
Signed-off-by: Jeff Johnson <jeff.johnson@oss.qualcomm.com>