crypto: x86/cast6 - drop dependency on glue helper

Replace the glue helper dependency with implementations of ECB and CBC
based on the new CPP macros, which avoid the need for indirect calls.

Acked-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>