Summary

This PR fixes UART reset, clock-disable, and IRQ pending-clear helpers when the STM32 HAL v2 driver is enabled.

This PR fixes the following bug:

• Use the HAL v2 RCC and Cortex/NVIC helper APIs for UART7/USART6.
• Breaking changes

The HAL v2 build does not provide the legacy helper implementation used by these paths. Without this change, UART deinitialization and interrupt handling for the affected peripherals do not compile or behave correctly on STM32C5 HAL v2 targets.

Dependencies and split

• This is an independent, generic HAL v2 UART fix.
• PR feat(xiao): add Seeed XIAO STM32C5 board support #3048 (XIAO STM32C5 board support) enables a C5 HAL v2 build of the shared UART wrapper; because C5 exposes USART6/UART7 symbols, this compatibility fix should be merged together with, or before, feat(xiao): add Seeed XIAO STM32C5 board support #3048 for a clean build.
• It does not depend on PR feat(usb): add STM32C5 HAL v2 USB device support #3059 (STM32C5 USB HAL v2 support), the UF2 recipe PR, or Arduino_Tools PR Make Serialx instance generic #122.

Validation

• The change is limited to the HAL v2 conditional paths in libraries/SrcWrapper/src/stm32/uart.c.
• Hardware validation and CI builds will be provided by the normal CI matrix.

Code formatting

• AStyle formatting is unchanged; CI should verify the repository formatting checks.

Closing issues

None.