drm/sched: Add dependency tracking

drm/sched: Add dependency tracking

Instead of just a callback we can just glue in the gem helpers that
panfrost, v3d and lima currently use. There's really not that many
ways to skin this cat.

v2/3: Rebased.

v4: Repaint this shed. The functions are now called _add_dependency()
and _add_implicit_dependency()

Reviewed-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com> (v3)
Reviewed-by: Steven Price <steven.price@arm.com> (v1)
Acked-by: Melissa Wen <mwen@igalia.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: "Christian König" <christian.koenig@amd.com>
Cc: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
Cc: Lee Jones <lee.jones@linaro.org>
Cc: Nirmoy Das <nirmoy.aiemd@gmail.com>
Cc: Boris Brezillon <boris.brezillon@collabora.com>
Cc: Luben Tuikov <luben.tuikov@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: linux-media@vger.kernel.org
Cc: linaro-mm-sig@lists.linaro.org
Link: https://patchwork.freedesktop.org/patch/msgid/20210805104705.862416-5-daniel.vetter@ffwll.ch