drm/amdgpu: fix potential memory leak during navi12 deinitialization

Navi12 HDCP & DTM deinitialization needs continue to free bo if already
created though initialized flag is not set.

Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Jiawei Gu <Jiawei.Gu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>