dts: clock_control: add mp2 rcc binding

Introduce DeviceTree binding for the STM32MP2 RCC clock controller,
enabling support for STM32MP2-specific clock configuration in Zephyr.
Update Kconfig.stm32 to add a dependency on STM32MP2 configuration,
allowing the use of STM32 LL RCC features when targeting STM32MP2
devices.
Add header for STM32MP2 per peripheral clock definitions.

Signed-off-by: Youssef Zini <youssef.zini@savoirfairelinux.com>