Make I2C code more robust

[ahtn]

Recover from SDA stuck low:

From section 3.1.16 of the I2C spec:

If the data line (SDA) is stuck LOW, the master should send nine clock pulses. The device that held the bus LOW should release it sometime within those nine clocks. If not, then use the HW reset or cycle power to clear the bus.

Refrences:

• I2C-bus specification and user manual