crypto: ux500 - memmove the right size

The hash buffer is really HASH_BLOCK_SIZE bytes, someone
must have thought that memmove takes n*u32 words by mistake.
Tests work as good/bad as before after this patch.

Cc: Joakim Bech <joakim.bech@linaro.org>
Cc: stable@vger.kernel.org
Reported-by: David Binderman <linuxdev.baldrick@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>