drm/scheduler: fix drm_sched_job_add_implicit_dependencies

drm/scheduler: fix drm_sched_job_add_implicit_dependencies

Trivial fix since we now need to grab a reference to the fence we have
added. Previously the dma_resv function where doing that for us.

Signed-off-by: Christian König <christian.koenig@amd.com>
Fixes: 9c2ba265352a ("drm/scheduler: use new iterator in drm_sched_job_add_implicit_dependencies v2")
Link: https://patchwork.freedesktop.org/patch/msgid/20211019112706.27769-1-christian.koenig@amd.com
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reported-by: Nicolas Frattaroli <frattaroli.nicolas@gmail.com>
References: https://lore.kernel.org/dri-devel/2023306.UmlnhvANQh@archbook/
Tested-by: Nicolas Frattaroli <frattaroli.nicolas@gmail.com>