gpu: host1x: hw: intr_hw: Remove create_workqueue

gpu: host1x: hw: intr_hw: Remove create_workqueue

System workqueues have been able to handle high level of concurrency
for a long time now and there's no reason to use dedicated workqueues
just to gain concurrency. Since the workqueue host->intr_wq is involved
in sync point interrupts, and sync point wait and is not being used on
a memory reclaim path, dedicated host->intr_wq has been replaced with the
use of system_wq.

Unlike a dedicated per-cpu workqueue created with create_workqueue(),
system_wq allows multiple work items to overlap executions even on
the same CPU; however, a per-cpu workqueue doesn't have any CPU
locality or global ordering guarantees unless the target CPU is
explicitly specified and thus the increase of local concurrency
shouldn't make any difference.

cancel_work_sync() has been used  in _host1x_free_syncpt_irq() to ensure
that no work is pending by the time exit path runs.

Signed-off-by: Bhaktipriya Shridhar <bhaktipriya96@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>