ath9k: don't trigger spectral scan when not enabled

Doing so enables the FFT generation without prior
configuration, leading to an IRQ storm caused by
invalid (or at least unwanted) PHY errors.
Signed-off-by: Zefir Kurtisi <zefir.kurtisi@neratec.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

drivers/net/wireless/ath/ath9k/common-spectral.c

@@ -742,6 +742,9 @@ void ath9k_cmn_spectral_scan_trigger(struct ath_common *common,
 		return;
 	}
 
+	if (!spec_priv->spec_config.enabled)
+		return;
+
 	ath_ps_ops(common)->wakeup(common);
 	rxfilter = ath9k_hw_getrxfilter(ah);
 	ath9k_hw_setrxfilter(ah, rxfilter |