lantiq: un-macro the image building code

target/linux/lantiq/image/Makefile

target/linux/lantiq/image/tp-link.mk

target/linux/lantiq/xrx200/profiles/00-default.mk

target/linux/lantiq/xrx200/profiles/arv.mk

target/linux/lantiq/xrx200/profiles/lantiq.mk

target/linux/lantiq/xrx200/profiles/tplink.mk

target/linux/lantiq/xrx200/target.mk

target/linux/lantiq/xway/profiles/00-default.mk

target/linux/lantiq/xway/profiles/arv.mk

target/linux/lantiq/xway/profiles/audiocodes.mk

target/linux/lantiq/xway/profiles/aztech.mk

target/linux/lantiq/xway/profiles/buffalo.mk

target/linux/lantiq/xway/profiles/gigaset.mk

target/linux/lantiq/xway/profiles/lantiq.mk

target/linux/lantiq/xway/profiles/zte.mk

target/linux/lantiq/xway/profiles/zyxel.mk