wcn36xx: Uninitialized variable in wcn36xx_change_opchannel()

This code needs "channel" to be initialized to NULL for it to work
correctly.

Fixes: d6f27466 ("wcn36xx: Track the band and channel we are tuned to")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Bryan O'Donoghue <bryan.odonghue@linaro.org>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/20220201125941.GA22458@kili

drivers/net/wireless/ath/wcn36xx/main.c

@@ -394,7 +394,7 @@ static void wcn36xx_change_opchannel(struct wcn36xx *wcn, int ch)
 	struct ieee80211_vif *vif = NULL;
 	struct wcn36xx_vif *tmp;
 	struct ieee80211_supported_band *band;
-	struct ieee80211_channel *channel;
+	struct ieee80211_channel *channel = NULL;
 	unsigned long flags;
 	int i, j;