drm/scheduler: Add drm_sched_job_cleanup

This patch adds a new API to clean up the scheduler job resources. This
is primarliy needed in cases the job was created but was not queued to
the scheduler queue. Additionally with this change, the layer which
creates the scheduler job also gets to free up the job's resources and
this entails moving the dma_fence_put(finished_fence) to the drivers
ops free handler routines.

Signed-off-by: Sharat Masetty <smasetty@codeaurora.org>
Reviewed-by: Christian König <christian.koenig@amd.com>
Acked-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>