drm/i915: Check intel_contexts to avoid one extra pointer chase

As we store the intel_context on the request (rq->hw_context), we can
simply compare that against the local intel_context for the
i915->kernel_context rather than using the rq->gem_context.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: NMika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180601094002.13329-1-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/i915_gem_context.c

@@ -610,7 +610,7 @@ static bool engine_has_kernel_context_barrier(struct intel_engine_cs *engine)
 
 		any_active = true;
 
-		if (rq->gem_context == i915->kernel_context)
+		if (rq->hw_context == ce)
 			continue;
 
 		/*