drm/amdgpu: split ip suspend into 2 phases

We need to do some IPs earlier to deal with ordering issues
similar to how resume is split into two phases. Do DCE first
to deal with atomic, then do the rest.

Acked-by: Harry Wentland <harry.wentland@amd.com>
Reviewed-and-tested-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>