[IPV4]: Pass the net pointer to the arp_req_set_proxy()

This one will need to set the IPV4_DEVCONF_ALL(PROXY_ARP), but
there's no ways to get the net right in place, so we have to
pull one from the inet_ioctl's struct sock.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index 5089a36..03633b7 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -798,7 +798,7 @@
 		case SIOCDARP:
 		case SIOCGARP:
 		case SIOCSARP:
-			err = arp_ioctl(cmd, (void __user *)arg);
+			err = arp_ioctl(sk->sk_net, cmd, (void __user *)arg);
 			break;
 		case SIOCGIFADDR:
 		case SIOCSIFADDR: