crypto: crypto4xx - pointer arithmetic overhaul

This patch improves the readability of various functions,
by replacing various void* pointers declarations with
their respective structs *. This makes it possible to go
for the eye-friendly array-indexing methods.

Signed-off-by: Christian Lamparter <chunkeey@googlemail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>