<fix>[utils]: get nic speed from file if get nic speed failed use ethtool
<fix>[utils]: get nic speed from file if get nic speed failed use ethtool

Resolves: ZSTAC-47193

Change-Id: I746368636274777769637a68696a686c75756861

zstackio/zstack-utility,zstackio/zstack-utility,zstackio/zstack-utility