boards/arm/mikroe_clicker_2: enable the console driver

The MikroE clicker 2 board selects the `uart4` node as `zephyr,console` in
the `chosen` node. This required one additional option to be y-selected on
Kconfig side so that printf/stdout etc. hooks are properly installed:
* CONFIG_UART_CONSOLE

Without that, no console output is observed.

Signed-off-by: Filip Kokosinski <fkokosinski@antmicro.com>