drm/scheduler: bind job earlier to scheduler

Update job earlier with the scheduler it is supposed to be scheduled on.

Otherwise we could incorrectly optimize dependencies when moving an
entity from one scheduler to another.

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Nayan Deshmukh <nayan26deshmukh@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>