crypto: sahara - pass on error condition

A failure of sahara_hw_descriptor_create() with -EINVAL due to scatter list
out of bounds/invalid would not be reported back. This patch just passes on
the -EINVAL so it is visible in sahara_queue_manage().

Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>