In CPU definitions we should not be explicilty naming peripheral modules to use
via USEMODULE (one should use FEATURES_PROVIDED instead).
Plus add missing cpu_init() and periph_init() methods.
This commit removes periph_hwrng support from the pic32mx cpu builds as
pic32mx does not have hwrng only pic32mz does.
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>