uapi: add missing netconf.h to export list

Add netconf.h for use by iproute2.
Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Acked-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/uapi/linux/Kbuild

@@ -258,6 +258,7 @@ header-y += neighbour.h
 header-y += net.h
 header-y += net_dropmon.h
 header-y += net_tstamp.h
+header-y += netconf.h
 header-y += netdevice.h
 header-y += netfilter.h
 header-y += netfilter_arp.h