drm/i915: Do a full device reset after being wedged

We only call unset_wedged on the global reset path (since it's a global
operation), so if we are terminally wedged and wish to reset, take the
full device reset path rather than the quicker individual engine resets.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180903083337.13134-1-chris@chris-wilson.co.uk