crypto: aspeed - fix build error when only CRYPTO_DEV_ASPEED is enabled

Fix build error within the following configs setting:
- CONFIG_CRYPTO_DEV_ASPEED=y
- CONFIG_CRYPTO_DEV_ASPEED_HACE_HASH is not set
- CONFIG_CRYPTO_DEV_ASPEED_HACE_CRYPTO is not set

Error messages:
make[4]: *** No rule to make target 'drivers/crypto/aspeed/aspeed_crypto.o'
, needed by 'drivers/crypto/aspeed/built-in.a'.
make[4]: Target '__build' not remade because of errors.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Neal Liu <neal_liu@aspeedtech.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>