The rxmonitor hook is called on each received packet. This can get very,
very busy as the tx/rx/chanbusy registers are thus read each time a packet
is received.
Instead, shuffle out the true per-packet processing which is needed and move
the rest of the ANI processing into a periodic event which runs every 100ms
by default.
sys/dev/ath/ath_hal/ar5416/ is getting very crowded and further
commits will make it even more crowded. Now is a good time to
shuffle these files out before any more extensive work is done
on them.
Create an ar9003 directory whilst I'm here; ar9003 specific
chipset code will eventually live there.