drm/i915: Assert that we do create the deferred context

In order to convince static analyzers that the allocation function
returns an error or sets ce->state, assert that it is set afterwards.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170105153023.30575-2-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/intel_lrc.c

@@ -781,6 +781,7 @@ static int execlists_context_pin(struct intel_engine_cs *engine,
 		if (ret)
 			goto err;
 	}
+	GEM_BUG_ON(!ce->state);
 
 	flags = PIN_GLOBAL;
 	if (ctx->ggtt_offset_bias)