qcacmn: Check return value for channel conversion

It may return NULL, which pass to another function and dereference it.
Check return value, don't pass to another function if return value is
NULL.

Change-Id: Ib2e87231bb724c5631c12e9bee98c22d4dcc9bf2
CRs-Fixed: 2233639

os_if/linux/p2p/src/wlan_cfg80211_p2p.c

@@ -286,6 +286,11 @@ static void wlan_p2p_event_callback(void *user_data,
 
 	chan = ieee80211_get_channel(wdev->wiphy,
 				     wlan_chan_to_freq(p2p_event->chan));
+	if (!chan) {
+		cfg80211_err("channel conversion failed");
+		goto fail;
+	}
+
 	if (p2p_event->roc_event == ROC_EVENT_READY_ON_CHAN) {
 		cfg80211_ready_on_channel(wdev,
 			p2p_event->cookie, chan,