powerpc/crc32: expose CRC32 functions through lib

powerpc/crc32: expose CRC32 functions through lib

Move the powerpc CRC32C assembly code into the lib directory and wire it
up to the library interface.  This allows it to be used without going
through the crypto API.  It remains usable via the crypto API too via
the shash algorithms that use the library interface.  Thus all the
arch-specific "shash" code becomes unnecessary and is removed.

Note: to see the diff from arch/powerpc/crypto/crc32c-vpmsum_glue.c to
arch/powerpc/lib/crc32-glue.c, view this commit with 'git show -M10'.

Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20241202010844.144356-9-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>