lib/crypto: s390/ghash: Migrate optimized code into library

lib/crypto: s390/ghash: Migrate optimized code into library

Remove the "ghash-s390" crypto_shash algorithm, and replace it with an
implementation of ghash_blocks_arch() for the GHASH library.

This makes the GHASH library be optimized with CPACF.  It also greatly
reduces the amount of s390-specific glue code that is needed, and it
fixes the issue where this GHASH optimization was disabled by default.

Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20260319061723.1140720-14-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>