MIPS: lantiq: export soc type

The voice and dsl drivers need to know which SoC we are running on.

Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
Patchwork: http://patchwork.linux-mips.org/patch/8046/


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