qcacmn: os_if: Replace explicit comparison to NULL

Per the Linux Kernel coding style, as enforced by the kernel
checkpatch script, pointers should not be explicitly compared to
NULL. Therefore within os_if replace any such comparisons with logical
operations performed on the pointer itself.

Change-Id: I1cf6f897d1d2722d112dd3f802d789652373eaed
CRs-Fixed: 2418254

os_if/linux/scan/src/wlan_cfg80211_scan.c

@@ -718,7 +718,7 @@ static QDF_STATUS wlan_scan_request_dequeue(
 
 	cfg80211_debug("Dequeue Scan id: %d", scan_id);
 
-	if ((source == NULL) || (req == NULL)) {
+	if ((!source) || (!req)) {
 		cfg80211_err("source or request is NULL");
 		return QDF_STATUS_E_NULL_VALUE;
 	}