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/security.h b/security/selinux/include/security.h
index 39337af..a33437b 100644
--- a/security/selinux/include/security.h
+++ b/security/selinux/include/security.h
@@ -77,8 +77,7 @@
 int security_port_sid(u16 domain, u16 type, u8 protocol, u16 port,
 	u32 *out_sid);
 
-int security_netif_sid(char *name, u32 *if_sid,
-	u32 *msg_sid);
+int security_netif_sid(char *name, u32 *if_sid);
 
 int security_node_sid(u16 domain, void *addr, u32 addrlen,
 	u32 *out_sid);