boards: arm: nucleo_h723zg board enabling usart2
boards: arm: nucleo_h723zg board enabling usart2

This enables defines the usart2 on PD5, PD6 pins
of the nucleo stm32h723zg target board. Pins are available
on the CN9 pin6 & 4 of the MB1364 nucleo144

Signed-off-by: Francois Ramu <b83adc7f8a23ee911a37fcb61c4033581aae0b7a@st.com>

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