crypto: inside-secure - improve the counter computation

A counter is given to the engine when finishing hash computation. It
currently uses the blocksize while it counts the number of 64 bytes
blocks given to the engine. This works well for all algorithms so far,
as SHA1, SHA224 and SHA256 all have a blocksize of 64 bytes, but others
algorithms such as SHA512 wouldn't work.

Signed-off-by: Antoine Tenart <antoine.tenart@bootlin.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>