The net80211 stack was providing a 'beacon miss timeout' value (in ms)

The net80211 stack was providing a 'beacon miss timeout' value (in ms)
which specified how much time may elapse without beacons before drivers
begin searching for a new AP.

Drivers convert this timeout value into the amount of beacons they're allowed
to miss. Having the stack provide this number upfront simplifies things.

ok mpi@