arm64: dts: st: add timer nodes on stm32mp257f-ev1

arm64: dts: st: add timer nodes on stm32mp257f-ev1

Configure timer nodes on stm32mp257f-ev1:
- Timer3 CH2 is available on mikroBUS connector for PWM
- timer8 CH1, timer8 CH4, timer10 CH1 and timer12 CH2 are available
  on EXPANSION connector.
Timers are kept disabled by default, so the pins can be used for any
other purpose (and the timers can be assigned to any of the processors).
Arbitrary choice is to use all these timers as PWM (or counter on
internal clock signal), except for timer10 that is configured with
CH1 as an input (for capture).

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Link: https://lore.kernel.org/r/20250110091922.980627-9-fabrice.gasnier@foss.st.com
Signed-off-by: Alexandre Torgue <alexandre.torgue@foss.st.com>