SELinux: Convert the netif code to use ifindex values

The current SELinux netif code requires the caller have a valid net_device
struct pointer to lookup network interface information.  However, we don't
always have a valid net_device pointer so convert the netif code to use
the ifindex values we always have as part of the sk_buff.  This patch also
removes the default message SID from the network interface record, it is
not being used and therefore is "dead code".

Signed-off-by: Paul Moore <paul.moore@hp.com>
Signed-off-by: James Morris <jmorris@namei.org>
diff --git a/security/selinux/include/objsec.h b/security/selinux/include/objsec.h
index 4138a80..2d0a92e9 100644
--- a/security/selinux/include/objsec.h
+++ b/security/selinux/include/objsec.h
@@ -96,9 +96,8 @@
 };
 
 struct netif_security_struct {
-	struct net_device *dev;		/* back pointer */
-	u32 if_sid;			/* SID for this interface */
-	u32 msg_sid;			/* default SID for messages received on this interface */
+	int ifindex;			/* device index */
+	u32 sid;			/* SID for this interface */
 };
 
 struct sk_security_struct {