wifi: ath11k: fix ath11k_mac_op_remain_on_channel() stack usage

When compiling with clang 16.0.6, I've noticed the following:

drivers/net/wireless/ath/ath11k/mac.c:8903:12: warning: stack frame
size (1032) exceeds limit (1024) in 'ath11k_mac_op_remain_on_channel'
[-Wframe-larger-than]
static int ath11k_mac_op_remain_on_channel(struct ieee80211_hw *hw,
           ^
68/1032 (6.59%) spills, 964/1032 (93.41%) variables

So switch to kzalloc()'ed instance of 'struct scan_req_params' like
it's done in 'ath11k_mac_op_hw_scan()'. Compile tested only.
Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
Acked-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/20230926042906.13725-1-dmantipov@yandex.ru

drivers/net/wireless/ath/ath11k/mac.c

@@ -8905,7 +8905,7 @@ static int ath11k_mac_op_remain_on_channel(struct ieee80211_hw *hw,
 {
 	struct ath11k *ar = hw->priv;
 	struct ath11k_vif *arvif = ath11k_vif_to_arvif(vif);
-	struct scan_req_params arg;
+	struct scan_req_params *arg;
 	int ret;
 	u32 scan_time_msec;
 
@@ -8937,27 +8937,31 @@ static int ath11k_mac_op_remain_on_channel(struct ieee80211_hw *hw,
 
 	scan_time_msec = ar->hw->wiphy->max_remain_on_channel_duration * 2;
 
-	memset(&arg, 0, sizeof(arg));
-	ath11k_wmi_start_scan_init(ar, &arg);
-	arg.num_chan = 1;
-	arg.chan_list = kcalloc(arg.num_chan, sizeof(*arg.chan_list),
-				GFP_KERNEL);
-	if (!arg.chan_list) {
+	arg = kzalloc(sizeof(*arg), GFP_KERNEL);
+	if (!arg) {
 		ret = -ENOMEM;
 		goto exit;
 	}
+	ath11k_wmi_start_scan_init(ar, arg);
+	arg->num_chan = 1;
+	arg->chan_list = kcalloc(arg->num_chan, sizeof(*arg->chan_list),
+				 GFP_KERNEL);
+	if (!arg->chan_list) {
+		ret = -ENOMEM;
+		goto free_arg;
+	}
 
-	arg.vdev_id = arvif->vdev_id;
-	arg.scan_id = ATH11K_SCAN_ID;
-	arg.chan_list[0] = chan->center_freq;
-	arg.dwell_time_active = scan_time_msec;
-	arg.dwell_time_passive = scan_time_msec;
-	arg.max_scan_time = scan_time_msec;
-	arg.scan_flags |= WMI_SCAN_FLAG_PASSIVE;
-	arg.scan_flags |= WMI_SCAN_FILTER_PROBE_REQ;
-	arg.burst_duration = duration;
-
-	ret = ath11k_start_scan(ar, &arg);
+	arg->vdev_id = arvif->vdev_id;
+	arg->scan_id = ATH11K_SCAN_ID;
+	arg->chan_list[0] = chan->center_freq;
+	arg->dwell_time_active = scan_time_msec;
+	arg->dwell_time_passive = scan_time_msec;
+	arg->max_scan_time = scan_time_msec;
+	arg->scan_flags |= WMI_SCAN_FLAG_PASSIVE;
+	arg->scan_flags |= WMI_SCAN_FILTER_PROBE_REQ;
+	arg->burst_duration = duration;
+
+	ret = ath11k_start_scan(ar, arg);
 	if (ret) {
 		ath11k_warn(ar->ab, "failed to start roc scan: %d\n", ret);
 
@@ -8983,7 +8987,9 @@ static int ath11k_mac_op_remain_on_channel(struct ieee80211_hw *hw,
 	ret = 0;
 
 free_chan_list:
-	kfree(arg.chan_list);
+	kfree(arg->chan_list);
+free_arg:
+	kfree(arg);
 exit:
 	mutex_unlock(&ar->conf_mutex);
 	return ret;