64 bit access is unaffected but for 32 bit access, swap high and
low words.  Similarly for 16 bit access, reverse the order of the
four possible words, and for 8 bit access reverse the order of byte
accesses.
Signed-off-by: Paul Martin <paul.martin@codethink.co.uk>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9630/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>