fix(i2c.py): remove exception for valid API call

[bhass1]

Fixes Issue #359

I considered converting it to a self.log.warning(), but the API documentation states a readlen of 0 is valid so it doesn't make sense to warn the developer about that.

Blame indicates these lines are 8 years old (https://github.com/eblot/pyftdi/commit/0701df62455583927cc91092c91de8840670f9f5), so it was probably just overlooked, unnecessary developer safety net.

P.S. Great work on this library!!!! 🎉 🎉 🎉

Tested with FTDI FT2232HQ found in the Tigard