soc: arm: stm32h5: support SWO

In case of stm32h5 both LL_DBGMCU_EnableTraceClock() and
LL_DBGMCU_SetTracePinAssignment() need to be called in order to properly
configure SWO output.

Select HAS_SWO, so that logging over SWO can be enabled.

Tested with ST's fork of openocd [1].

[1] https://github.com/STMicroelectronics/OpenOCD



Signed-off-by: Marcin Niestroj <m.niestroj@emb.dev>