MIPS: APRP: Split VPE loader into separate files.

Split the VPE functionality in preparation for adding support
for CMP platforms. Common functions remain in the original file
and a new file contains code specific to platforms that do not
have a CMP present.

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>
Signed-off-by: John Crispin <blogic@openwrt.org>
Patchwork: http://patchwork.linux-mips.org/patch/6094/