ath10k: don't call quiet mode if it's not implemented

qca6174 and wmi-tlv doesn't have quiet mode
implemented. Don't even attempt to call it. This
fixes a warning when bringing first interface up:

  failed to set quiet mode period 100 duarion 0 enabled 0 ret -95

Fixes: 8515b5c79a54 ("ath10k: configure thermal throttle while powering up")
Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

drivers/net/wireless/ath/ath10k/thermal.c

@@ -140,6 +140,9 @@ void ath10k_thermal_set_throttling(struct ath10k *ar)
 
 	lockdep_assert_held(&ar->conf_mutex);
 
+	if (!ar->wmi.ops->gen_pdev_set_quiet_mode)
+		return;
+
 	if (ar->state != ATH10K_STATE_ON)
 		return;