Compilation for pic32mx and pic32mz did not include the path
to cpu/mips_pic32_common/include. Also,
cpu/mips_pic32_common/Makefile.include was never parsed. It was
found that mips32r2_common and mips_pic32_common are both defining
similar parameters for linkers which cause issues if both
Makefile.include get parsed.
Signed-off-by: Francois Berder <francois.berder@imgtec.com>
