Revert "drm/amdgpu: Disable gfx off if VCN is busy"

This reverts commit 3fded222
This is work around for vcn1 only. Currently vcn1 has separate
begin_use and idle work handle.

Signed-off-by: James Zhu <James.Zhu@amd.com>
Tested-by: changzhu <Changfeng.Zhu@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>