dt-bindings: mfd: stm32-lptimer: Add support for stm32mp25

dt-bindings: mfd: stm32-lptimer: Add support for stm32mp25

Add a new stm32mp25 compatible to stm32-lptimer dt-bindings, to support
STM32MP25 SoC. Some features has been updated or added to the low-power
timer:
- new capture compare channels
- up to two PWM channels
- PWM input capture
- peripheral interconnect in stm32mp25 has been updated (new triggers).
- registers/bits has been added or revisited (IER access).
So introduce a new compatible to handle this diversity.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Reviewed-by: "Rob Herring (Arm)" <robh@kernel.org>
Link: https://lore.kernel.org/r/20250429125133.1574167-2-fabrice.gasnier@foss.st.com
Signed-off-by: Lee Jones <lee@kernel.org>