Merge pull request #1736 from haukepetersen/fix_stm32f1_somecleanup

boards/iot-lab_M3/Makefile

boards/iot-lab_M3/drivers/Makefile

boards/iot-lab_M3/drivers/at86rf231_driver.c

boards/iot-lab_M3/include/board.h

boards/iot-lab_M3/include/periph_conf.h

cpu/stm32f1/periph/spi.c

drivers/at86rf231/at86rf231.c

drivers/at86rf231/at86rf231_rx.c

drivers/at86rf231/at86rf231_spi.c

drivers/at86rf231/at86rf231_tx.c

drivers/at86rf231/include/at86rf231_arch.h

drivers/at86rf231/include/at86rf231_spi.h

drivers/include/at86rf231.h

drivers/include/at86rf231/at86rf231_settings.h