boards: lora_e5_dev_board: set defaults for blackmagicprobe
boards: lora_e5_dev_board: set defaults for blackmagicprobe

This sets the commonly used serial port alias for blackmagicprobe, as
well as the flag to reset on connect, so that flashing works in low
power.

Signed-off-by: Fabio Baltieri <161d407f4dc681bfd4aedb33b8273b2aafd727bc@gmail.com>

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