Virtual WIFI, stake 5: origin detection.

Unfortunately, MAC80211HWSIM leaves MAC ADDRESS as the only method of detecting packet origin.
This is sad, because on more sophisticated systems, like ours is about to be, modification of
mac address is simple, but will kill communication. The only way to fix this would be to
extend MAC80211 packets with HWSIM_ATTR_RADIO_ID, which is there, but for some reason has
been decided to not be included in the packet.

Change-Id: I59cc7de64d0f9a34d4a9d2d9ecdbdeeda84d71da