crypto: sha256-generic - move to generic glue implementation

This updates the generic SHA-256 implementation to use the
new shared SHA-256 glue code.

It also implements a .finup hook crypto_sha256_finup() and exports
it to other modules. The import and export() functions and the
.statesize member are dropped, since the default implementation
is perfectly suitable for this module.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/include/crypto/sha.h b/include/crypto/sha.h
index a754cdd7..e28c4b5 100644
--- a/include/crypto/sha.h
+++ b/include/crypto/sha.h
@@ -93,6 +93,9 @@
 extern int crypto_sha256_update(struct shash_desc *desc, const u8 *data,
 			      unsigned int len);
 
+extern int crypto_sha256_finup(struct shash_desc *desc, const u8 *data,
+			       unsigned int len, u8 *hash);
+
 extern int crypto_sha512_update(struct shash_desc *desc, const u8 *data,
 			      unsigned int len);
 #endif