Added a cancellation channel to interrupt a goroutine

[RomanAvdeenko]

I had to check with arp request 5 networks 192.x.x.x/ 23 and 2 networks 192.x.x.x/ 22. I did it sequentially in a loop, and I ran into a problem that sometimes func PingOverIface () hangs without returning a result, as if somewhere to lock a goroutine. I added a cancellation channel and that solved my problem.