staging: octeon: drop atomic usage from rx counters

We have only one NAPI poll running at a time, so virtual port rx counters
can be updated normally.

Update of rx_dropped can still race with the gathering of statistics,
but full accuracy is not required there.

Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Acked-by: David Daney <david.daney@cavium.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>