crypto: shash - Make descsize a run-time attribute

This patch changes descsize to a run-time attribute so that
implementations can change it in their init functions.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/include/crypto/internal/hash.h b/include/crypto/internal/hash.h
index 069b93e..2d1b10f 100644
--- a/include/crypto/internal/hash.h
+++ b/include/crypto/internal/hash.h
@@ -135,7 +135,7 @@
 
 static inline struct crypto_shash *__crypto_shash_cast(struct crypto_tfm *tfm)
 {
-	return (struct crypto_shash *)tfm;
+	return container_of(tfm, struct crypto_shash, base);
 }
 
 #endif	/* _CRYPTO_INTERNAL_HASH_H */