o catch one place where we were not using ath_chan_change to
switch channels; this fixes a problem where the channel
settings were not being correctly reported in captured packets
o return unique channel identification in the channel flags;
ethereal gets confused if you return merged flags (e.g. ofdm,
cck, and 2Ghz) (this is workaround and should be removed if
we can ever cleanup radiotap consumers)
o correct short/long preamble flag state for rx and treat tx
the same--use a new hwflags array that gives us the data
based on the h/w rate index/cookie
o add gross hack to handle radiotap capture of frames that
come in with hardware padding; should be replaced by a
flag in the radiotap header and more smarts in the apps
that decode radiotap data