r368167:
  NVME: Don't try to swap data on little endian machines.  These swapping
  functions violate BUSDMA contract - we cannot write to armed (by
  bus_dmamap_sync(PRE_..)) buffers. Remove them at least from little endian
  machines until a better solution will be developed.
r368187:
  Unbreak r368167 in userland. Decorate unused arguments.
r368203:
  Always use the __unused attribute even for potentially unused parameters.