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>