drm/amdgpu: Call doorbell index init on device initialization

Also call functioin amdgpu_device_doorbell_init after
amdgpu_device_ip_early_init because the former depends
on the later to set up asic-specific init_doorbell_index
function

Signed-off-by: Oak Zeng <ozeng@amd.com>
Suggested-by: Felix Kuehling <Felix.Kuehling@amd.com>
Suggested-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>