[CRYPTO] blkcipher: Merge ablkcipher and blkcipher into one option/module

With the impending addition of the givcipher type, both blkcipher and
ablkcipher algorithms will use it to create givcipher objects.  As such
it no longer makes sense to split the system between ablkcipher and
blkcipher.  In particular, both ablkcipher.c and blkcipher.c would need
to use the givcipher type which has to reside in ablkcipher.c since it
shares much code with it.

This patch merges the two Kconfig options as well as the modules into one.

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