drm/i915/execlists: Add a GEM_TRACE to show when the context is completed

Include a GEM_TRACE to show when the context is complete and we advance
the ELSP port.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180221151553.9054-1-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/intel_lrc.c

@@ -881,6 +881,9 @@ static void execlists_submission_tasklet(unsigned long data)
 				trace_i915_request_out(rq);
 				i915_request_put(rq);
 
+				GEM_TRACE("%s completed ctx=%d\n",
+					  engine->name, port->context_id);
+
 				execlists_port_complete(execlists, port);
 			} else {
 				port_set(port, port_pack(rq, count));