Based upon a report by Andrew Morton and code analysis done
by Jarek Poplawski.
This reverts 33f807ba0d ("[NETPOLL]:
Kill NETPOLL_RX_DROP, set but never tested.") and
c7b6ea24b4 ("[NETPOLL]: Don't need
rx_flags.").
The rx_flags did get tested for zero vs. non-zero and therefore we do
need those tests and that code which sets NETPOLL_RX_DROP et al.
Signed-off-by: David S. Miller <davem@davemloft.net>
d9452e9f81