crypto: scatterwalk - Set the chain pointer indication bit

The scatterwalk_crypto_chain function invokes the scatterwalk_sg_chain
function to chain two scatterlists, but the chain pointer indication
bit is not set.  When the resulting scatterlist is used, for example,
by sg_nents to count the number of scatterlist entries, a segfault occurs
because sg_nents does not follow the chain pointer to the chained scatterlist.

Update scatterwalk_sg_chain to set the chain pointer indication bit as is
done by the sg_chain function.

Cc: stable@vger.kernel.org
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>