crypto: sha512 - Replace sha512_generic with wrapper around SHA-512 library

Delete crypto/sha512_generic.c, which provided "generic" SHA-384 and
SHA-512 crypto_shash algorithms.  Replace it with crypto/sha512.c which
provides SHA-384, SHA-512, HMAC-SHA384, and HMAC-SHA512 crypto_shash
algorithms using the corresponding library functions.

This is a prerequisite for migrating all the arch-optimized SHA-512 code
(which is almost 3000 lines) to lib/crypto/ rather than duplicating it.

Since the replacement crypto_shash algorithms are implemented using the
(potentially arch-optimized) library functions, give them
cra_driver_names ending with "-lib" rather than "-generic".  Update
crypto/testmgr.c and one odd driver to take this change in driver name
into account.  Besides these cases which are accounted for, there are no
known cases where the cra_driver_name was being depended on.

This change does mean that the abstract partial block handling code in
crypto/shash.c, which got added in 6.16, no longer gets used.  But
that's fine; the library has to implement the partial block handling
anyway, and it's better to do it in the library since the block size and
other properties of the algorithm are all fixed at compile time there,
resulting in more streamlined code.

Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20250630160320.2888-6-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>

crypto/Kconfig

@@ -1002,8 +1002,10 @@ config CRYPTO_SHA256
 config CRYPTO_SHA512
 	tristate "SHA-384 and SHA-512"
 	select CRYPTO_HASH
+	select CRYPTO_LIB_SHA512
 	help
-	  SHA-384 and SHA-512 secure hash algorithms (FIPS 180, ISO/IEC 10118-3)
+	  SHA-384 and SHA-512 secure hash algorithms (FIPS 180, ISO/IEC
+	  10118-3), including HMAC support.
 
 config CRYPTO_SHA3
 	tristate "SHA-3"