Initialize doorbell index for asics vi and cik

v2: Use enum definition instead of hardcoded number
Signed-off-by: NOak Zeng <ozeng@amd.com>
Suggested-by: NFelix Kuehling <Felix.Kuehling@amd.com>
Suggested-by: NAlex Deucher <alexander.deucher@amd.com>
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>