drm/i915: Avoid promoting a simulated hang to 'wedged'

It appears that a beneficial side-effect of Mika's more accurate hangman
work is to speed up hang detection and execution. This exposes a bug in
the reset code that then treats repeated simulated hangs as an
indication that the machine is wedged. Jiggle the code around so that we
only do the simulation processing from the hangcheck and avoid confusing
it with a real hang.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=65060


Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>