core: hash: fix hash backends erasing ctx function pointers

core/hash/md4.c

@@ -259,8 +259,6 @@ void md4_finish(struct b_hash_ctx *ctx, void *out, size_t max)
 	OUT(&result[4], ctx->ctx_state.md4.b)
 	OUT(&result[8], ctx->ctx_state.md4.c)
 	OUT(&result[12], ctx->ctx_state.md4.d)
-
-	memset(ctx, 0, sizeof(*ctx));
 }
 
 struct b_hash_function_ops z__b_md4_ops = {

core/hash/sha1.c

@@ -257,7 +257,6 @@ static void sha_finish(struct b_hash_ctx *context, void *out, size_t max)
 
 	memcpy(out, digest, b_min(size_t, sizeof digest, max));
 	/* Wipe variables */
-	memset(context, '\0', sizeof(*context));
 	memset(&finalcount, '\0', sizeof(finalcount));
 }