ramips: 6.1: ralink: fix ethernet driver with 6.1

ramips: 6.1: ralink: fix ethernet driver with 6.1

Fixes errors in the form of:
  make[9]: Entering directory '/home/nick/openwrt/build_dir/target-mipsel_24kc_musl/linux-ramips_mt7620/linux-6.1.77'
    CC      drivers/net/ethernet/ralink/mtk_eth_soc.o
  drivers/net/ethernet/ralink/mtk_eth_soc.c: In function 'fe_init':
  drivers/net/ethernet/ralink/mtk_eth_soc.c:1368:51: warning: passing argument 2 of 'of_get_mac_address' discards 'const' qualifier from pointer target type [-Wdiscarded-qualifiers]
   1368 |         of_get_mac_address(priv->dev->of_node, dev->dev_addr);
        |                                                ~~~^~~~~~~~~~
  In file included from drivers/net/ethernet/ralink/mtk_eth_soc.c:26:
  ./include/linux/of_net.h:16:59: note: expected 'u8 *' {aka 'unsigned char *'} but argument is of type 'const unsigned char *'
     16 | extern int of_get_mac_address(struct device_node *np, u8 *mac);
        |                                                       ~~~~^~~
  drivers/net/ethernet/ralink/mtk_eth_soc.c: In function 'fe_probe':
  drivers/net/ethernet/ralink/mtk_eth_soc.c:1641:9: error: too many arguments to function 'netif_napi_add'
   1641 |         netif_napi_add(netdev, &priv->rx_napi, fe_poll, napi_weight);
        |         ^~~~~~~~~~~~~~
  In file included from ./include/linux/etherdevice.h:21,
                   from drivers/net/ethernet/ralink/mtk_eth_soc.c:21:
  ./include/linux/netdevice.h:2611:1: note: declared here
   2611 | netif_napi_add(struct net_device *dev, struct napi_struct *napi,
        | ^~~~~~~~~~~~~~

Signed-off-by: Mieczyslaw Nalewaj <namiltd@yahoo.com>
[split commit and rewrite commit message]
Signed-off-by: Nick Hainke <vincent@systemli.org>