boards/arm/ruuvi_ruuvitag: enable the console driver

The Ruuvitag board selects the `uart0` node as `zephyr,console` in the
`chosen` node. This required three options to be y-selected on Kconfig side
so that printf/stdout etc. hooks are properly installed:
* CONFIG_CONSOLE
* CONFIG_SERIAL
* CONFIG_UART_CONSOLE

Without that, no console output is observed.

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