net: calxedaxgmac: remove some unused statistic counters
net: calxedaxgmac: remove some unused statistic counters

rx_sa_filter_fail and tx_undeflow events are unused and impossible
to occur based on how the h/w is used. We never filter on source MAC
address and TX store and forward mode prevents underflow events.

Reported-by: Lennert Buytenhek <8858498612e3a522354216649776e3032dcb7e5b@wantstofly.org>
Signed-off-by: Rob Herring <aa00819e304141d872f2e4b1c4be422ea3abbfe1@calxeda.com>
Signed-off-by: David S. Miller <fe08d3c717adf2ae63592e4c9aec6e3e404d8e3e@davemloft.net>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs