drm/i915: Dequeue execlists on a new request if any port is available

If the second ELSP port is available, schedule the execlists tasklet to
see if the new request can occupy it.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170124110009.28947-7-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/intel_lrc.c

@@ -653,7 +653,7 @@ static void execlists_submit_request(struct drm_i915_gem_request *request)
 
 	if (insert_request(&request->priotree, &engine->execlist_queue)) {
 		engine->execlist_first = &request->priotree.node;
-		if (execlists_elsp_idle(engine))
+		if (execlists_elsp_ready(engine))
 			tasklet_hi_schedule(&engine->irq_tasklet);
 	}