Add properties for i2c2 and i2c8 available on the stm32mp257f-ev1.
i2c2 is enabled since several devices are attached to it while
i2c8 is kept disabled since only used via the gpio expansion connector.
Signed-off-by: Alain Volmat <alain.volmat@foss.st.com>
Signed-off-by: Alexandre Torgue <alexandre.torgue@foss.st.com>