drm/i915/guc: Fix request re-submission after reset

drm/i915/guc: Fix request re-submission after reset

In order to ensure no missed interrupts we must first re-direct
the interrupts to GuC, and only then re-submit the requests to
be replayed after a GPU reset. Otherwise context switch can fire
before GuC has been set up to receive it triggering more hangs.

v2: Rebase.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: Oscar Mateo <oscar.mateo@intel.com>
Cc: Sagar Arun Kamble <sagar.a.kamble@intel.com>
Cc: Arkadiusz Hiler <arkadiusz.hiler@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/20170309132005.1317-1-tvrtko.ursulin@linux.intel.com