[Make-wifi-fast] Carrying the CoDel timestamp into the driver

[Toke Høiland-Jørgensen]

Hi Michal

In your mac80211 FQ-CoDel patch, you put the CoDel timestamp into a
union with the vif pointer in struct ieee80211_tx_info. This means the
timestamp is not available in the driver. I'm experimenting with some
changes where having the enqueue time available would be useful.

Do you have any good ideas as to where else we could store the enqueue
time somewhere the driver can retrieve it?

-Toke