i2c: stm32f7: add support for stm32mp25 soc

The stm32mp25 has only a single interrupt line used for both
events and errors. In order to cope with that, reorganise the
error handling code so that it can be called either from the
common handler (used in case of SoC having only a single IT line)
and the error handler for others.
The CR1 register also embeds a new FMP bit, necessary when running
at Fast Mode Plus frequency. This bit should be used instead of
the SYSCFG bit used on other platforms.
Add a new compatible to distinguish between the SoCs and two
boolean within the setup structure in order to know if the
platform has a single/multiple IT lines and if the FMP bit
within CR1 is available or not.

Signed-off-by: Valentin Caron <valentin.caron@foss.st.com>
Signed-off-by: Alain Volmat <alain.volmat@foss.st.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>