vmnet: fix wireless device detection

Mainline commit c304eddcecfe ("net: wrap the wireless pointers in struct
net_device in an ifdef") in 5.19-rc1 makess ieee80211_ptr member present in
struct net_device only if CONFIG_CFG80211 is enabled. Do the same for the
code testing its value in VNetBridgeIsDeviceWireless() to fix build against
kernel with CONFIG_CFG80211 disabled. Functionally, this is equivalent to
newly introduced wireless_group_needed() helper in upstream kernel code.

We can use the same code also for older kernels as with CONFIG_CFG80211
disabled, the pointer should be null anyway.

vmnet-only/bridge.c

@@ -809,10 +809,14 @@ static Bool
 VNetBridgeIsDeviceWireless(struct net_device *dev) //IN: sock
 {
 #if defined(CONFIG_WIRELESS_EXT)
-   return dev->ieee80211_ptr != NULL || dev->wireless_handlers != NULL;
-#else
-   return dev->ieee80211_ptr != NULL;
+   if (dev->wireless_handlers)
+      return true;
 #endif
+#if IS_ENABLED(CONFIG_CFG80211)
+   if (dev->ieee80211_ptr)
+      return true;
+#endif
+   return false;
 }