i2c_api implementation has been changed in order to support single byte reads and writes (the latter are used in I2CEeprom module used in CI tests, and this caused that tests-i2c-api were failing). These operations (single byte transfers) are not possible to achieve with the driver from nrf5 SDK (nrf_drv_twi), so the new implementation uses TWI HAL only.

Author: nvlsianpu