xen: netfront: ethtool stats fields should be unsigned long

Fixup the rx_gso_checksum_fixup field added in e0ce4af920eb to be
unsigned long as suggested by Ben Hutchings in
<1298919198.2569.14.camel@bwh-desktop>

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Cc: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/xen-netfront.c

@@ -122,7 +122,7 @@ struct netfront_info {
 	struct mmu_update rx_mmu[NET_RX_RING_SIZE];
 
 	/* Statistics */
-	int rx_gso_checksum_fixup;
+	unsigned long rx_gso_checksum_fixup;
 };
 
 struct netfront_rx_info {