drm/etnaviv: Use scheduler dependency handling

drm/etnaviv: Use scheduler dependency handling

We need to pull the drm_sched_job_init much earlier, but that's very
minor surgery.

v2: Actually fix up cleanup paths by calling drm_sched_job_init, which
I wanted to to in the previous round (and did, for all other drivers).
Spotted by Lucas.

v3: Rebase over renamed functions to add dependencies.

v4: Rebase over patches from Christian.

v5: More rebasing over work from Christian.

Acked-by: Lucas Stach <l.stach@pengutronix.de>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Lucas Stach <l.stach@pengutronix.de>
Cc: Russell King <linux+etnaviv@armlinux.org.uk>
Cc: Christian Gmeiner <christian.gmeiner@gmail.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: "Christian König" <christian.koenig@amd.com>
Cc: etnaviv@lists.freedesktop.org
Cc: linux-media@vger.kernel.org
Cc: linaro-mm-sig@lists.linaro.org
Link: https://patchwork.freedesktop.org/patch/msgid/20220331204651.2699107-2-daniel.vetter@ffwll.ch