crypto: ctr - Use chainiv on raw counter mode

Raw counter mode only works with chainiv, which is no longer
the default IV generator on SMP machines.  This broke raw counter
mode as it can no longer instantiate as a givcipher.

This patch fixes it by always picking chainiv on raw counter
mode.  This is based on the diagnosis and a patch by Huang
Ying.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>