drm/i915/execlists: Push the tasklet kick after reset to reset_finish

drm/i915/execlists: Push the tasklet kick after reset to reset_finish

In the unlikely case where we have failed to keep submitting to the GPU,
we end up with the ELSP queue empty but a pending queue of requests.
Here, we skip the per-engine reset as there is no guilty request, but in
doing so we also skip the engine restart leaving ourselves with a
permanently hung engine. A quick way to recover is by moving the tasklet
kick to execlists_reset_finish() (from init_hw). We still emit the error
on hanging, so the error is not lost but we should be able to recover.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Michel Thierry <michel.thierry@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180604073441.6737-2-chris@chris-wilson.co.uk
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>