crypto: ccree - remove special handling of chained sg

We were handling chained scattergather lists with specialized code
needlessly as the regular sg APIs handle them just fine. The code
handling this also had an (unused) code path with a use-before-init
error, flagged by Coverity.

Remove all special handling of chained sg and leave their handling
to the regular sg APIs.

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>