Add IFF_UP device flag constant in NetlinkConstants.

Bug: 163492391
Test: atest NetworkStaticLibTests
Change-Id: I81965261e8ccecd680504d3d98378973d6f44436
diff --git a/staticlibs/device/com/android/net/module/util/netlink/NetlinkConstants.java b/staticlibs/device/com/android/net/module/util/netlink/NetlinkConstants.java
index 83a82b7..c44a5b4 100644
--- a/staticlibs/device/com/android/net/module/util/netlink/NetlinkConstants.java
+++ b/staticlibs/device/com/android/net/module/util/netlink/NetlinkConstants.java
@@ -151,6 +151,7 @@
     public static final int RTMGRP_ND_USEROPT = 1 << (RTNLGRP_ND_USEROPT - 1);
 
     // Device flags.
+    public static final int IFF_UP       = 1 << 0;
     public static final int IFF_LOWER_UP = 1 << 16;
 
     // Known values for struct rtmsg rtm_protocol.