A lot of crypto code needs to read/write a 32-bit/64-bit words in a
specific gender.  Many of them open code them by reading/writing one
byte at a time.  This patch converts all the applicable usages over
to use the standard byte order macros.

This is based on a previous patch by Denis Vlasenko.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>