drm/amd/amdgpu: Set VCE/UVD off during late init

Forces VCE/UVD off during late init to ensure they're powered off
correctly during boot.

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