drivers/dose: don't default to UART0
drivers/dose: don't default to UART0

The first UART is usually used for the shell, so don't default
DOSE on it.

OTAkeys/RIOT,kYc0o/RIOT,miri64/RIOT,OTAkeys/RIOT,ant9000/RIOT,kaspar030/RIOT,miri64/RIOT,RIOT-OS/RIOT,RIOT-OS/RIOT,jasonatran/RIOT,OTAkeys/RIOT,authmillenon/RIOT,kYc0o/RIOT,kaspar030/RIOT,jasonatran/RIOT,kaspar030/RIOT,authmillenon/RIOT,kYc0o/RIOT,OlegHahm/RIOT,jasonatran/RIOT,RIOT-OS/RIOT,jasonatran/RIOT,OTAkeys/RIOT,RIOT-OS/RIOT,kYc0o/RIOT,authmillenon/RIOT,miri64/RIOT,ant9000/RIOT,jasonatran/RIOT,ant9000/RIOT,RIOT-OS/RIOT,ant9000/RIOT,OlegHahm/RIOT,kaspar030/RIOT,OlegHahm/RIOT,kaspar030/RIOT,OlegHahm/RIOT,authmillenon/RIOT,authmillenon/RIOT,OTAkeys/RIOT,miri64/RIOT,OlegHahm/RIOT,ant9000/RIOT,miri64/RIOT,kYc0o/RIOT,authmillenon/RIOT