Fix virtual wireless (MultiSSID)

Fix virtual wireless (MultiSSID)

This commit fixes several issues with MultiSSID:
- It didn't work properly with RT-N branch and the new brcm drivers.
- If the virtual SSID was using another bridge than LAN (br0) the new wireless interface was never added to the bridge.

Typical behaviours seen was one of the following: BSSID was null, not able to join the network or network not being visible altogether.

Add "wireless" and "wl" optional services:
- wireless: stop/start the wireless service, re-initialising the interfaces
- wl: load/unload the wl drivers and re-initalise the various wireless interfaces

Tested on Asus RT-N66U and Asus RT-N16

Note: When using virtual wireless on dual band routers, it is best to only set it on one adapter. 5GHz virtual wireless shows some strange behaviours. It's no surprise Asus disabled it all together.