dist/tools: add "RESET_PIN" value for the dwm1001
dist/tools: add "RESET_PIN" value for the dwm1001

Set "RESET_PIN" to 21 if the selected board is "dwm1001".

ant9000/RIOT,jasonatran/RIOT,jasonatran/RIOT,kaspar030/RIOT,ant9000/RIOT,ant9000/RIOT,jasonatran/RIOT,RIOT-OS/RIOT,jasonatran/RIOT,kaspar030/RIOT,kaspar030/RIOT,kaspar030/RIOT,ant9000/RIOT,kaspar030/RIOT,RIOT-OS/RIOT,RIOT-OS/RIOT,jasonatran/RIOT,RIOT-OS/RIOT,ant9000/RIOT,RIOT-OS/RIOT