* arch/arm/src/nrf52/hardware/nrf52_twi.h: fix typo * arch/arm/src/nrf52/nrf52_i2c.c: add interrupts support and some debug messages * boards/arm/nrf52/nrf52840-dk: add support for hts221 and lsm303agr; boards/arm/nrf52/nrf52840-dk: fix issues noted by nxstyle