drm/i915/guc: Assert guc->stage_desc_pool is allocated

Silence smatch by demonstrating that guc->stage_desc_pool is allocated
following a successful guc_stage_desc_pool_create(),

drivers/gpu/drm/i915/i915_guc_submission.c:1293 i915_guc_submission_init() error: we previously assumed 'guc->stage_desc_pool' could be null (see line 1261)
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Oscar Mateo <oscar.mateo@intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171106114833.31199-1-chris@chris-wilson.co.ukReviewed-by: Michal Wajdeczko <michal.wajdeczko@intel.com>

drivers/gpu/drm/i915/i915_guc_submission.c

@@ -1264,10 +1264,16 @@ int i915_guc_submission_init(struct drm_i915_private *dev_priv)
 	ret = guc_stage_desc_pool_create(guc);
 	if (ret)
 		return ret;
+	/*
+	 * Keep static analysers happy, let them know that we allocated the
+	 * vma after testing that it didn't exist earlier.
+	 */
+	GEM_BUG_ON(!guc->stage_desc_pool);
 
 	ret = guc_shared_data_create(guc);
 	if (ret)
 		goto err_stage_desc_pool;
+	GEM_BUG_ON(!guc->shared_data);
 
 	ret = intel_guc_log_create(guc);
 	if (ret < 0)
@@ -1276,10 +1282,12 @@ int i915_guc_submission_init(struct drm_i915_private *dev_priv)
 	ret = guc_preempt_work_create(guc);
 	if (ret)
 		goto err_log;
+	GEM_BUG_ON(!guc->preempt_wq);
 
 	ret = guc_ads_create(guc);
 	if (ret < 0)
 		goto err_wq;
+	GEM_BUG_ON(!guc->ads_vma);
 
 	return 0;