drm: fix gpu scheduler link order

It should initialize before the drivers using it.

Signed-off-by: Christian König <christian.koenig@amd.com>
Bug: https://bugs.freedesktop.org/show_bug.cgi?id=104736
Reviewed-by: Mike Lothian <mike@fireburn.co.uk>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>