LSM: Convert security_initcall() into DEFINE_LSM()

Instead of using argument-based initializers, switch to defining the
contents of struct lsm_info on a per-LSM basis. This also drops
the final use of the now inaccurate "initcall" naming.

Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Casey Schaufler <casey@schaufler-ca.com>
Reviewed-by: James Morris <james.morris@microsoft.com>
Signed-off-by: James Morris <james.morris@microsoft.com>

security/selinux/hooks.c

@@ -7202,7 +7202,9 @@ void selinux_complete_init(void)
 
 /* SELinux requires early initialization in order to label
    all processes and objects when they are created. */
-security_initcall(selinux_init);
+DEFINE_LSM(selinux) = {
+	.init = selinux_init,
+};
 
 #if defined(CONFIG_NETFILTER)