i2c: refactoring
i2c: refactoring

* Removed check_mikrobus_index function
* Changed error messages to be consistent with the rest of the code

Signed-off-by: Francois Berder <59eaf4bb0211c66c3d7532da6d77ecf42a779d82@outlook.fr>

francois-berder/LetMeCreate,francois-berder/LetMeCreate