Update Ezo_i2c_util.cpp

[JRHemmen]

Added a case to the switch statement in print_success_or_error for NOT_READ_CMD. Otherwise would not compile in PlatformIO using ESP IDF Framework.

[JRHemmen]

This will resolve https://github.com/Atlas-Scientific/Ezo_I2c_lib/issues/13

[JRHemmen]

Updated wording around errors, still room for improvement

[Atlas-Scientific]

This looks great, thank you so much!