Merge pull request #10268 from SemjonKerner/add_nrf154

boards/common/nrf52/Makefile.dep

boards/common/nrf52/include/cfg_timer_default.h

boards/nrf52840dk/Makefile.dep

boards/nrf52840dk/Makefile.features

cpu/nrf52/Makefile

cpu/nrf52/Makefile.dep

cpu/nrf52/Makefile.include

cpu/nrf52/include/nrf802154.h

cpu/nrf52/radio/nrf802154/Makefile

cpu/nrf52/radio/nrf802154/nrf802154.c

drivers/include/net/netdev/ieee802154.h

drivers/netdev_ieee802154/netdev_ieee802154.c

examples/default/Makefile

sys/auto_init/auto_init.c

sys/auto_init/netif/auto_init_nrf802154.c

sys/include/net/ieee802154.h