crypto: ccree - drop legacy ivgen support

ccree had a mechanism for IV generation which was not compatible
with the Linux seqiv or echainiv iv generator and was never used
in any of the upstream versions so drop all the code implementing it.

Signed-off-by: Gilad Ben-Yossef <gilad@benyossef.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>