Add initial support for Decawave DW1000
IEEE 802.15.4-2011 UWB transceiver.
Driver has basic functionality. Additional functions such
as reading out timestamps and delayed TX were implemented
for test purposes, but also require support in the 802154
subsystem.
Register, sub-register, and defaults defines in the file
ieee802154_dw1000_regs.h are taken from the Decawave's
DW1000 driver for the Mynewt OS.
Signed-off-by: Johann Fischer <j.fischer@phytec.de>
