As we drop the engine-pm on retiring, that may happen while there are
still CS events in the buffer. As such we cannot assert the engine is
still active on reset, until we know that the current request is still
in flight.

Closes: https://gitlab.freedesktop.org/drm/intel/issues/1338Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Andi Shyti <andi.shyti@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200227204727.2009346-1-chris@chris-wilson.co.uk