rpi-config: fix config variables with the same initial name being overwritten
rpi-config: fix config variables with the same initial name being overwritten

agherzan/meta-raspberrypi,agherzan/meta-raspberrypi,schnitzeltony/meta-raspberrypi,kraj/meta-raspberrypi,schnitzeltony/meta-raspberrypi,kraj/meta-raspberrypi,kraj/meta-raspberrypi,agherzan/meta-raspberrypi,leon-anavi/meta-raspberrypi,leon-anavi/meta-raspberrypi,schnitzeltony/meta-raspberrypi,agherzan/meta-raspberrypi,agherzan/meta-raspberrypi,agherzan/meta-raspberrypi,leon-anavi/meta-raspberrypi