boards: M5Stack Core2 module suppport

This Pull-Request enables support for the M5Stack Core2 hardware.
The module features a LCD display, touchscreen, battery, USB-Port,
8MB RAM and 16MB Flash.
Basic features are working. Please refere to the board documentation
for details.

Signed-off-by: Martin Kiepfer <mrmarteng@teleschirm.org>

gpio: gpio_axp192: fix dependecy between GET_DIRECTION and GET_CONFIG
configuration

Latest unit gpio get_direction unit test failes, as get_direction api
internally requires get_config functionality. This commit fixes this
dependecy.

Signed-off-by: Martin Kiepfer <m.kiepfer@teleschirm.org>