backports: handle argument type change of get_rxnfc in struct ethtool_ops

backports: handle argument type change of get_rxnfc in struct ethtool_ops

In kernel 3.2 an argument type of function pointer get_rxnfc in
struct ethtool_ops changed from void to u32.
Address this by putting ifdef around the code.

commit 815c7db5c809ea3d5735de3131ecdf758b0e14ff
Author: Ben Hutchings <bhutchings@solarflare.com>
Date:   Tue Sep 6 13:49:12 2011 +0000

    ethtool: Clean up definitions of rule location arrays in RX NFC

git describe --contains 815c7db5c809ea3d5735de3131ecdf758b0e14ff
v3.2-rc1~129^2~272

Signed-off-by: Stefan Assmann <sassmann@kpanic.de>
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>