drm/i915/guc: Don't drop ce->guc_active.lock when unwinding context

Don't drop ce->guc_active.lock when unwinding a context after reset.
At one point we had to drop this because of a lock inversion but that is
no longer the case. It is much safer to hold the lock so let's do that.

Fixes: eb5e7da ("drm/i915/guc: Reset implementation for new GuC interface")
Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210909164744.31249-5-matthew.brost@intel.com

drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c

@@ -813,8 +813,6 @@ __unwind_incomplete_requests(struct intel_context *ce)
 			continue;
 
 		list_del_init(&rq->sched.link);
-		spin_unlock(&ce->guc_active.lock);
-
 		__i915_request_unsubmit(rq);
 
 		/* Push the request back into the queue for later resubmission. */
@@ -827,8 +825,6 @@ __unwind_incomplete_requests(struct intel_context *ce)
 
 		list_add(&rq->sched.link, pl);
 		set_bit(I915_FENCE_FLAG_PQUEUE, &rq->fence.flags);
-
-		spin_lock(&ce->guc_active.lock);
 	}
 	spin_unlock(&ce->guc_active.lock);
 	spin_unlock_irqrestore(&sched_engine->lock, flags);