drm/i915/guc: Don't leak stage descriptor pool on init failure

In case of failure during GuC clients creation, we forget to
cleanup earlier pool allocation. Use proper teardown to fix that.

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Michal Winiarski <michal.winiarski@intel.com>
Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20180605120547.16468-1-michal.wajdeczko@intel.com

drivers/gpu/drm/i915/intel_guc_submission.c

@@ -1157,7 +1157,7 @@ int intel_guc_submission_init(struct intel_guc *guc)
 	WARN_ON(!guc_verify_doorbells(guc));
 	ret = guc_clients_create(guc);
 	if (ret)
-		return ret;
+		goto err_pool;
 
 	for_each_engine(engine, dev_priv, id) {
 		guc->preempt_work[id].engine = engine;
@@ -1166,6 +1166,9 @@ int intel_guc_submission_init(struct intel_guc *guc)
 
 	return 0;
 
+err_pool:
+	guc_stage_desc_pool_destroy(guc);
+	return ret;
 }
 
 void intel_guc_submission_fini(struct intel_guc *guc)