IB/rxe: make the variable static

The variable rxe_net_notifier is only used in the file rxe_net.c. So
remove it from rxe_net.h file and make it static in the file rxe_net.c.

CC: Srinivas Eeda <srinivas.eeda@oracle.com>
CC: Junxiao Bi <junxiao.bi@oracle.com>
Signed-off-by: NZhu Yanjun <yanjun.zhu@oracle.com>
Reviewed-by: NBart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: NYuval Shaia <yuval.shaia@oracle.com>
Signed-off-by: NJason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/sw/rxe/rxe_net.c

@@ -707,7 +707,7 @@ static int rxe_notify(struct notifier_block *not_blk,
 	return NOTIFY_OK;
 }
 
-struct notifier_block rxe_net_notifier = {
+static struct notifier_block rxe_net_notifier = {
 	.notifier_call = rxe_notify,
 };
 

drivers/infiniband/sw/rxe/rxe_net.h

@@ -43,7 +43,6 @@ struct rxe_recv_sockets {
 	struct socket *sk6;
 };
 
-extern struct notifier_block rxe_net_notifier;
 void rxe_release_udp_tunnel(struct socket *sk);
 
 struct rxe_dev *rxe_net_add(struct net_device *ndev);