samples: display: Enable display support in ST7789V sample
samples: display: Enable display support in ST7789V sample

Enable display support for ST7789V sample by setting CONFIG_DISPLAY in
prj.conf.

Signed-off-by: Jan Van Winkel <d648848808a4d751aff880668aa63d2d9d94a5a4@dxplore.eu>

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