(prevents inclusion and also issues warning)
Changes to some source files to remove references to common headers.
Changes to rng.h to make guard symbols the same in f2 and f4.
Most peripheral headers simply include <libopencm3/stm32/memorymap.h>
which, like the rest of libopencm3 requires the correct compiler define
flag to be set. A few peripherals were directly including the platform
include, libopencm3/stm32/xx/memorymap.h, and in some of those cases it
wasn't even correctly including the correct platform. (Likely the
result of copy/paste errors)
These direct includes have been eliminated
