crypto: powerpc/md5 - assembler

This is the assembler code for the MD5 implementation.
Handling of algorithm constants has been slightly
changed to reduce register usage and make better use
of cores with multiple ALUs. Thus they are stored as
delta values.

Signed-off-by: Markus Stockhausen <stockhausen@collogia.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>