drm/amd/powerplay: move clockgating to after ungating power in pp for uvd/vce

Cannot set clockgating state before ungating power.

Signed-off-by: Tom St Denis <tom.stdenis@amd.com>
Reviewed-by: Rex Zhu <Rex.Zhu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>