Add a new compatible string to support MP25 SoC.

On MP1 SoC, RNB signal (NAND controller signal) and NWAIT signal (PSRAM
controller signal) have been integrated together in the SoC. That means
that the NAND controller and the PSRAM controller (if the signal is
used) can not be used at the same time. On MP25 SoC, the 2 signals can
be used outside the SoC, so there is no more restrictions.

MP1 SoC also embeds revision 1.1 of the FMC2 IP when MP25 SoC embeds
revision 2.0 of the FMC2 IP.

MP25 SoC is also using PSCI OS-initiated mode, so allow a single
'power-domains' entry for STM32 FMC2. As MP1 will move on PSCI
OS-initiated mode, add this property as optional for all FMC2 variants.
Signed-off-by: Christophe Kerello <christophe.kerello@foss.st.com>
Link: https://lore.kernel.org/r/20240226101428.37791-2-christophe.kerello@foss.st.comSigned-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>