MIPS: lantiq: remove orphaned code

Now that all drivers are converted to OF we are able to remove some remaining
pieces of orphaned code.

Signed-off-by: John Crispin <blogic@openwrt.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/3841/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>