crypto: acomp - Add request chaining and virtual addresses

This adds request chaining and virtual address support to the
acomp interface.

It is identical to the ahash interface, except that a new flag
CRYPTO_ACOMP_REQ_NONDMA has been added to indicate that the
virtual addresses are not suitable for DMA.  This is because
all existing and potential acomp users can provide memory that
is suitable for DMA so there is no need for a fall-back copy
path.

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