Fix incompatible pointer type error in kernel 5.15+

By the kernel 5.15+, there are new patches for ethtool.
- https://patchwork.kernel.org/project/netdevbpf/list/?series=534709&state=%2A&archive=both

Adding those two dummy parameters will fix the following compile error
in the kernel 5.14 or below.

```
/home/awesometic/Developer/realtek-r8152-dkms/src/r8152.c:18530:18: error: initialization of ‘int (*)(struct net_device *, struct ethtool_coalesce *, struct kernel_ethtool_coalesce *, struct netlink_ext_ack *)’ from incompatible pointer type ‘int (*)(struct net_device *, struct ethtool_coalesce *)’ [-Werror=incompatible-pointer-types]
18530 |  .get_coalesce = rtl8152_get_coalesce,
      |                  ^~~~~~~~~~~~~~~~~~~~
/home/awesometic/Developer/realtek-r8152-dkms/src/r8152.c:18530:18: note: (near initialization for ‘ops.get_coalesce’)
/home/awesometic/Developer/realtek-r8152-dkms/src/r8152.c:18531:18: error: initialization of ‘int (*)(struct net_device *, struct ethtool_coalesce *, struct kernel_ethtool_coalesce *, struct netlink_ext_ack *)’ from incompatible pointer type ‘int (*)(struct net_device *, struct ethtool_coalesce *)’ [-Werror=incompatible-pointer-types]
18531 |  .set_coalesce = rtl8152_set_coalesce,
      |                  ^~~~~~~~~~~~~~~~~~~~
```

Signed-off-by: Deokgyu Yang <[email protected]>

src/r8152.c

@@ -18336,7 +18336,13 @@ static int rtl8152_nway_reset(struct net_device *dev)
 }
 
 static int rtl8152_get_coalesce(struct net_device *netdev,
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(5,15,0)
+				struct ethtool_coalesce *coalesce,
+				struct kernel_ethtool_coalesce *_kernel_coalesce,
+				struct netlink_ext_ack *_netlink_ack)
+#else
 				struct ethtool_coalesce *coalesce)
+#endif /* LINUX_VERSION_CODE >= KERNEL_VERSION(5,15,0) */
 {
 	struct r8152 *tp = netdev_priv(netdev);
 
@@ -18355,7 +18361,13 @@ static int rtl8152_get_coalesce(struct net_device *netdev,
 }
 
 static int rtl8152_set_coalesce(struct net_device *netdev,
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(5,15,0)
+				struct ethtool_coalesce *coalesce,
+				struct kernel_ethtool_coalesce *_kernel_coalesce,
+				struct netlink_ext_ack *_netlink_ack)
+#else
 				struct ethtool_coalesce *coalesce)
+#endif /* LINUX_VERSION_CODE >= KERNEL_VERSION(5,15,0) */
 {
 	struct r8152 *tp = netdev_priv(netdev);
 	u32 rx_coalesce_nsecs;