crypto: mv_cesa - fix hashing of chunks > 1920 bytes

This was broken by commit 7759995c (yes,
myself). The basic problem here is since the digest state is only saved
after the last chunk, the state array is only valid when handling the
first chunk of the next buffer. Broken since linux-3.0.

Signed-off-by: Phil Sutter <phil.sutter@viprinet.com>
Cc: <stable@kernel.org> # 3.1.x
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>