b/c/particle-mesh: move monofirmware setup to post_startup()
b/c/particle-mesh: move monofirmware setup to post_startup()

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