This commit adds I2C timeouts for nrf51 and nrf52 (but not yet for
others like nrf52840).
Tested on the PineTime, where I now got a timeout instead of hanging and
resetting due to a watchdog reset.
Found while working on the PineTime. For some reason it still kind of
works in most cases, but I was hitting this issue when interacting with
two different I2C devices (the touch sensor and the BMA421).
Ayke van Laethem
Kenneth Bell