v1:
implement new RAS ACA driver code framework.

v2:
- rename aca_bank_set to aca_banks.
- rename aca_source_xxx to aca_handle_xxx.

v3:
Optimize some function implementation details. (from Hawking's suggestion)
Signed-off-by: Yang Wang <kevinyang.wang@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>