Cleanup and update comments for output mark

This change updates the comments about the permission bits for IPsec
tunnel mode.

Bug: 116035464
Test: Compiles, comment-only change
Change-Id: I0a6a5b2e85f5703f9fe237b3c00919c1e1ed78bf
diff --git a/server/XfrmController.cpp b/server/XfrmController.cpp
index cf4d367..684f5e9 100644
--- a/server/XfrmController.cpp
+++ b/server/XfrmController.cpp
@@ -1304,7 +1304,8 @@
 // Network's netid. This allows outbound IPsec Tunnel mode packets to be correctly directed to a
 // preselected underlying Network. Packet as marked as protected from VPNs and have a network
 // explicitly selected to prevent interference or routing loops. Also set permission flag to
-// PERMISSION_SYSTEM to ensure we can use background/restricted networks.
+// PERMISSION_SYSTEM to ensure we can use background/restricted networks. Permission to use
+// restricted networks is checked in IpSecService.
 int XfrmController::fillNlAttrXfrmOutputMark(const __u32 underlyingNetId,
                                              nlattr_xfrm_output_mark* output_mark) {
     // Do not set if we were not given an output mark