wifi: rtw88: Un-embed dummy device

Embedding net_device into structures prohibits the usage of flexible
arrays in the net_device structure. For more details, see the discussion
at [1].

Un-embed the net_device from the private struct by converting it
into a pointer. Then use the leverage the new alloc_netdev_dummy()
helper to allocate and initialize dummy devices.

[1] https://lore.kernel.org/all/20240229225910.79e224cf@kernel.org/

Tested with RTL8723DE and RTL8822CE.
Signed-off-by: Breno Leitao <leitao@debian.org>
Acked-by: Ping-Ke Shih <pkshih@realtek.com>
Tested-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://msgid.link/20240425082910.2824393-1-leitao@debian.org

drivers/net/wireless/realtek/rtw88/pci.c

@@ -1682,12 +1682,16 @@ static int rtw_pci_napi_poll(struct napi_struct *napi, int budget)
 	return work_done;
 }
 
-static void rtw_pci_napi_init(struct rtw_dev *rtwdev)
+static int rtw_pci_napi_init(struct rtw_dev *rtwdev)
 {
 	struct rtw_pci *rtwpci = (struct rtw_pci *)rtwdev->priv;
 
-	init_dummy_netdev(&rtwpci->netdev);
-	netif_napi_add(&rtwpci->netdev, &rtwpci->napi, rtw_pci_napi_poll);
+	rtwpci->netdev = alloc_netdev_dummy(0);
+	if (!rtwpci->netdev)
+		return -ENOMEM;
+
+	netif_napi_add(rtwpci->netdev, &rtwpci->napi, rtw_pci_napi_poll);
+	return 0;
 }
 
 static void rtw_pci_napi_deinit(struct rtw_dev *rtwdev)
@@ -1696,6 +1700,7 @@ static void rtw_pci_napi_deinit(struct rtw_dev *rtwdev)
 
 	rtw_pci_napi_stop(rtwdev);
 	netif_napi_del(&rtwpci->napi);
+	free_netdev(rtwpci->netdev);
 }
 
 int rtw_pci_probe(struct pci_dev *pdev,
@@ -1745,7 +1750,11 @@ int rtw_pci_probe(struct pci_dev *pdev,
 		goto err_pci_declaim;
 	}
 
-	rtw_pci_napi_init(rtwdev);
+	ret = rtw_pci_napi_init(rtwdev);
+	if (ret) {
+		rtw_err(rtwdev, "failed to setup NAPI\n");
+		goto err_pci_declaim;
+	}
 
 	ret = rtw_chip_info_setup(rtwdev);
 	if (ret) {

drivers/net/wireless/realtek/rtw88/pci.h

@@ -215,7 +215,7 @@ struct rtw_pci {
 	bool running;
 
 	/* napi structure */
-	struct net_device netdev;
+	struct net_device *netdev;
 	struct napi_struct napi;
 
 	u16 rx_tag;