top: call cpus refresh after the first display delay

When the cpu utilization is displayed for the first time, the reading of the /proc/stat file is very close to each other, resulting in large fluctuations. The version before refactoring, such as v3.3.17, has a delay before reading the /proc/stat file for the second time, and the same delay is added here.

signed-off-by: zhoujie zhoujie133@huawei.com signed-off-by: he jingxian hejingxian@huawei.com