dmaengine: Revert "dmaengine: dmatest: Fix dmatest waiting less when interrupted"

dmaengine: Revert "dmaengine: dmatest: Fix dmatest waiting less when interrupted"

Several issues with this change:

* The analysis is flawed and it's unclear what problem is being
  fixed. There is no difference between wait_event_freezable_timeout()
  and wait_event_timeout() with respect to device interrupts. And of
  course "the interrupt notifying the finish of an operation happens
  during wait_event_freezable_timeout()" -- that's how it's supposed
  to work.

* The link at the "Closes:" tag appears to be an unrelated
  use-after-free in idxd.

* It introduces a regression: dmatest threads are meant to be
  freezable and this change breaks that.

See discussion here:
https://lore.kernel.org/dmaengine/878qpa13fe.fsf@AUSNATLYNCH.amd.com/

Fixes: e87ca16e9911 ("dmaengine: dmatest: Fix dmatest waiting less when interrupted")
Signed-off-by: Nathan Lynch <nathan.lynch@amd.com>
Link: https://lore.kernel.org/r/20250403-dmaengine-dmatest-revert-waiting-less-v1-1-8227c5a3d7c8@amd.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>