qcacmn: Add NULL check for 'pl_dev'

Currently 'pl_dev' is dereferenced without check for NULL in
get_pktlog_handle function in pktlog_internal.c

To address this issue add NULL check before dereferencing

Change-Id: Ic258db7bf1b404ff4f2d6c18abe775335074268b
CRs-Fixed: 2196058

utils/pktlog/pktlog_internal.c

@@ -370,7 +370,12 @@ A_STATUS process_tx_info(struct cdp_pdev *txrx_pdev, void *data)
 		return A_ERROR;
 	}
 
-	qdf_assert(pl_dev);
+	if (!pl_dev) {
+		pr_err("Invalid pktlog handle in %s\n", __func__);
+		qdf_assert(pl_dev);
+		return A_ERROR;
+	}
+
 	qdf_assert(data);
 
 	fw_data = (struct ol_fw_data *)data;