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

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

Add a new stm32mp25 compatible to stm32-timer dt-bindings in order to
support the STM32MP25 SoC. Some features has been added or updated in
the stm32-timer timer such as:
- hardware configuration and identification registers to read the timer
  version and capabilities (counter width, number of channels...)
- dithering mode (can be used to extend PWM resolution)
- input triggers list
- new counter modes
- various bit-field updates
- power-domains property
Timer trigger identifier can be up to 19 (from timer 20)

Acked-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Link: https://lore.kernel.org/r/20250110091922.980627-2-fabrice.gasnier@foss.st.com
Signed-off-by: Lee Jones <lee@kernel.org>