We were trying to be clever zapping out of the cache only the required
length out of scatter list on AEAD request completion and getting it
wrong.

As Knuth said: "when in douby, use brute force". Zap the whole length of
the scatter list.
Signed-off-by: Gilad Ben-Yossef <gilad@benyossef.com>
Cc: stable@vger.kernel.org # v4.19+
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>