ipconfig: add static to local variable

ic_dev_xid is only used in ipconfig.c

Cc: "David S. Miller" <davem@davemloft.net>
Cc: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Cc: netdev@vger.kernel.org
Signed-off-by: NFabian Frederick <fabf@skynet.be>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/ipconfig.c

@@ -143,7 +143,7 @@ __be32 ic_servaddr = NONE;	/* Boot server IP address */
 __be32 root_server_addr = NONE;	/* Address of NFS server */
 u8 root_server_path[256] = { 0, };	/* Path to mount as root */
 
-__be32 ic_dev_xid;		/* Device under configuration */
+static __be32 ic_dev_xid;		/* Device under configuration */
 
 /* vendor class identifier */
 static char vendor_class_identifier[253] __initdata;