selinux: mark some global variables __ro_after_init

All of these are never modified outside initcalls, so they can be
__ro_after_init.

Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
diff --git a/security/selinux/netlink.c b/security/selinux/netlink.c
index 621e2e9..1760aee 100644
--- a/security/selinux/netlink.c
+++ b/security/selinux/netlink.c
@@ -19,7 +19,7 @@
 
 #include "security.h"
 
-static struct sock *selnl;
+static struct sock *selnl __ro_after_init;
 
 static int selnl_msglen(int msgtype)
 {