crypto: authenc - don't leak pointers to authenc keys

In crypto_authenc_setkey we save pointers to the authenc keys in
a local variable of type struct crypto_authenc_keys and we don't
zeroize it after use. Fix this and don't leak pointers to the
authenc keys.
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/authenc.c

@@ -108,6 +108,7 @@ static int crypto_authenc_setkey(struct crypto_aead *authenc, const u8 *key,
 				       CRYPTO_TFM_RES_MASK);
 
 out:
+	memzero_explicit(&keys, sizeof(keys));
 	return err;
 
 badkey: