crypto: aspeed - Fix modular aspeed-acry

When aspeed-acry is enabled as a module it doesn't get built at
all.  Fix this by adding it to obj-m.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Reviewed-by: Neal Liu <neal_liu@aspeedtech.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>