Make if_ierrors updated whenever any of the following counters are
updated.
o Number of times NIC ran out of RX buffer descriptors
o Number of inbound packet errors
o Number of inbound packets that were chosen to be discarded
Previously only the discarded packet counter was used to update
if_ierrors. This change fixes wrong if_ierrors counter on
BCM570[0-4] controllers. For BCM5705 and later controllers bge(4)
already correctly counted it.

Reported by: Eugene Grosbein <egrosbein <> rdtc dot ru>