soc: gd32: Add HAS_SEGGER_RTT
soc: gd32: Add HAS_SEGGER_RTT

Enable SEGGER RTT for GigaDevice family.

Signed-off-by: Alex Sergeev <560d40af08985f446462a372f8eb4bf9fd2a1481@carbonrobotics.com>

zephyrproject-rtos/zephyr,galak/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,finikorg/zephyr,finikorg/zephyr,galak/zephyr,galak/zephyr,finikorg/zephyr,finikorg/zephyr