val create : unit -> Mirage_net.statscreate () returns a fresh set of zeroed counters
val rx : Mirage_net.stats -> int64 -> unitrx t size records that we received a packet of length size
val tx : Mirage_net.stats -> int64 -> unittx t size records that we transmitted a packet of length size
val reset : Mirage_net.stats -> unitreset t resets all packet counters in t to 0