MIPS: Add header files reference with path prefix

There are some common header files which are referenced locally
with #includenext method, includenext is tricky method and only
used on mips platform.

This patech removes includenext method, replace it with defailed
pathname prefix for header files.

This patch passes to compile on all mips platform with defconfig,
and is verified on my loongson64 box.

Changes:
--------
v2:
- Fix compiling issue on malta platform

Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: bibo mao <maobibo@loongson.cn>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

MIPS: Move headfiles to new location below arch/mips/include

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