lib: utils/i2c: Add generic I2C configuration library

Helper library to keep track of registered I2C adapters,
identified by dts offset, basic send/read functions and
adapter configuration (enable, set dividers, etc...).

Tested-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Alexandre Ghiti <alexandre.ghiti@canonical.com>
Tested-by: Alexandre Ghiti <alexandre.ghiti@canonical.com>
Signed-off-by: Nikita Shubin <n.shubin@yadro.com>