Fix memory leak in tee_svc_cryp_obj_copy()

The following Trusted App would lead to a memory leak in the TEE core:

  TEE_ObjectHandle o1, o2;
  TEE_AllocateTransientObject(TEE_TYPE_RSA_KEYPAIR, 256, &o1);
  TEE_GenerateKey(o1, 256, NULL, 0);
  TEE_AllocateTransientObject(TEE_TYPE_RSA_KEYPAIR, 256, &o2);
  TEE_CopyObjectAttributes(o2, o1);
  TEE_FreeTransientObject(o1);
  TEE_FreeTransientObject(o2);

The leak was introduced by commit ffe040395b13 ("Add crypto provider internal
API").

Signed-off-by: Jerome Forissier <jerome.forissier@linaro.org>
Reviewed-by: Jens Wiklander <jens.wiklander@linaro.org>
Reviewed-by: Pascal Brand <pascal.brand@linaro.org>
Tested-by: Pascal Brand <pascal.brand@linaro.org> (STM platform)