Squashed commit of the following:
wireless/bluetooth: Some small changes that gets to a clean compile by just eliminating some incorrect implementations (still with a lot of warnings. The logic is still incomplete but now not so lethal.
wireless/bluetooth: Restructuring: Connection interfaces should internal to wireless/bluetooth. include/nuttx/wireless/bt_conn.h removed and merged with wireless/bluetooth/bt_conn.h. Several fix to get closer to bt_netdev.c compiling. Need to design some not interfaces and use some existing interfaces to send and receiv packets.
wireless/bluetooth: Some organization with some network device compile errors fixed. Still not even close to compiling.
net/bluetooth: Fix numerous compile issues; Still open design issues with regard to the interface with the Bluetooth stack.
wireless/bluetooth: Create bt_netdev.c with a crude copy of mac802154_netdev.c. Does not not even compile yet.
include/nuttx/net: Add bluetooth.h. Content is not yet correct.
net/netpackets: Add bluetooth.h. Update net/bluetooth to use new socket address definition.
net/bluetooth: Some fixes for initial build.
net/bluetooth: Add initial support for Bluetooth sockets. The initial cut is just the a clone of the IEEE 802.15.4 socket support with name changes.
net/ieee802154: Fix some typos noted when cloning to create net/bluetooth.
