crypto: caam - remove dead code

- assoc_nents and src_nents are never zero when all_contig is false
- iv_contig is zero on the else branch

Signed-off-by: Cristian Stoica <cristian.stoica@freescale.com>
Reviewed-by: Richard Schmitt <richard.schmitt@freescale.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>