netdev2: use params parameter for setup

cpu/native/include/netdev2_tap.h

cpu/native/netdev2_tap/netdev2_tap.c

cpu/native/startup.c

drivers/at86rf2xx/at86rf2xx.c

drivers/at86rf2xx/at86rf2xx_getset.c

drivers/at86rf2xx/at86rf2xx_internal.c

drivers/at86rf2xx/at86rf2xx_netdev.c

drivers/encx24j600/encx24j600.c

drivers/ethos/ethos.c

drivers/include/at86rf2xx.h

drivers/include/encx24j600.h

drivers/include/ethos.h

drivers/include/xbee.h

drivers/xbee/xbee.c

sys/auto_init/netif/auto_init_at86rf2xx.c

sys/auto_init/netif/auto_init_xbee.c

tests/driver_at86rf2xx/main.c