[CRYPTO] rmd128: Fix endian problems

This patch is based on Sebastian Siewior's patch and
fixes endian issues making rmd128 work properly on
big-endian machines.

Signed-off-by: Adrian-Ken Rueegsegger <rueegsegger@swiss-it.ch>
Acked-by: Sebastian Siewior <sebastian@breakpoint.cc>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>