MIPS: APRP: Add RTLX API support for CMP platforms.

This patch adds RTLX API support for platforms having a CMP.

Signed-off-by: Deng-Cheng Zhu <dengcheng.zhu@imgtec.com>
Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>
Reviewed-by: Qais Yousef <Qais.Yousef@imgtec.com>
Patchwork: http://patchwork.linux-mips.org/patch/6095/


Reviewed-by: John Crispin <blogic@openwrt.org>