!12139 fix mobilenetv3 cpu train param

From: @wuxuejian
Reviewed-by: @liangchenghui,@c_34
Signed-off-by: @liangchenghui

model_zoo/official/cv/mobilenetv3/train.py

@@ -214,7 +214,7 @@ if __name__ == '__main__':
                   loss_scale_manager=loss_scale)
 
     cb = [Monitor(lr_init=lr.asnumpy())]
-    if args_opt.run_distribute:
+    if args_opt.run_distribute and args_opt.device_target != "CPU":
         ckpt_save_dir = config_gpu.save_checkpoint_path + "ckpt_" + str(get_rank()) + "/"
     else:
         ckpt_save_dir = config_gpu.save_checkpoint_path + "ckpt_" + "/"