wil6210: fix chan check in wil_p2p_listen

In wil_p2p_listen chan is checked to protect against NULL
pointer access only before setting channel = chan->hw_value.
Add a global parameter check to cover all accesses to chan.

Signed-off-by: Maya Erez <qca_merez@qca.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

drivers/net/wireless/ath/wil6210/p2p.c

@@ -114,8 +114,10 @@ int wil_p2p_listen(struct wil6210_priv *wil, unsigned int duration,
 	u8 channel = P2P_DMG_SOCIAL_CHANNEL;
 	int rc;
 
-	if (chan)
-		channel = chan->hw_value;
+	if (!chan)
+		return -EINVAL;
+
+	channel = chan->hw_value;
 
 	wil_dbg_misc(wil, "%s: duration %d\n", __func__, duration);