crypto: acomp - add driver-side scomp interface

Add a synchronous back-end (scomp) to acomp. This allows to easily
expose the already present compression algorithms in LKCF via acomp.

Signed-off-by: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>