DoNanoSleep 接口以微秒为单位，纳秒级别的在转换成微秒时被整除为0，
导致转换成tick时为0，导致延时时触发yield，导致延时时间超大
Close #I3Z9DP
Signed-off-by: Nzhushengle <zhushengle@huawei.com>
Change-Id: Ib662fdc80707be6040b2bb06a1b457344bd48b30