drm/sched: Rename drm_sched_free_job_queue to be more descriptive

The current name makes it sound like helper will free a queue, while what
it does is it enqueues the free job worker.

Rename it to drm_sched_run_free_queue to align with existing
drm_sched_run_job_queue.

Despite that creating an illusion there are two queues, while in reality
there is only one, at least it creates a consistent naming for the two
enqueuing helpers.

At the same time simplify the "if done" helper by dropping the suffix and
adding a double underscore prefix to the one which just enqueues.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Luben Tuikov <ltuikov89@gmail.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231102105538.391648-4-tvrtko.ursulin@linux.intel.com
Reviewed-by: Luben Tuikov <ltuikov89@gmail.com>
Signed-off-by: Luben Tuikov <ltuikov89@gmail.com>