to remove the frobbing that drivers must do in the hci_unit structure.
- driver provides a static const interface descriptor
- hci_unit is allocated by hci_attach() rather than part of softc
- statistics are compiled by driver and provided on request
- driver provides output methods and is responsible for output queue
- stack provides input methods and is responsible for input queue
- mutex is used to arbitrate device queue access
softc no longer contains 'struct device' by default
use 'device_t' instead of 'struct device *'
use device_xxx() accessor functions
remove casting of 'xxx_softc *' & 'struct device *'
use aprint_xxx_dev() routines
+ Initialize m_pkthdr.len, and increment if not escape charactor.
+ Call bcsp_start() if there is no transmitted packet.
+ Call m_adj() after debug print.
+ Reset the values of the Sequencing layer if link reset it.
