!21915 fix dqn GPU unnecessary ctx set

Merge pull request !21915 from caojian05/ms_master_dqn_bugfix

model_zoo/official/rl/dqn/train.py

@@ -49,7 +49,6 @@ if __name__ == "__main__":
     context.set_context(mode=context.GRAPH_MODE, device_target=args.device_target)
     if args.device_target == 'GPU':
         cfg = cfg_gpu
-        context.set_context(device_id=1)
 
     env = gym.make(cfg.game)
     env = env.unwrapped
@@ -105,4 +104,3 @@ if __name__ == "__main__":
     times_numpy = np.array(times)
 
     print(rewards_numpy.mean(), times_numpy.mean())
-