The low level routines can be used in different occasions, it will be
required when accessing PCI.
Note the difference between byteorder.h (inlined functions) and access.S
where the functions will be declared in the library archive librtemscpu.a.
Function names starting with _ are in library and can be referenced by
function pointers.
Signed-off-by: Daniel Hellstrom <daniel@gaisler.com>