[KA09] add keepalive offload permission to shell

This change adds PACKET_KEEPALIVE_OFFLOAD to shell, which allows
shell or code with shell permission identity to use privileged
tcp keepalive offload API.

Bug: 114151147
Test: -atest ConnectivityManagerTest#testCreateTcpKeepalive
      -build, flash, boot

Change-Id: Ib6660a5eaa72f83042596481452be4d415383f02
diff --git a/data/etc/privapp-permissions-platform.xml b/data/etc/privapp-permissions-platform.xml
index fcd5d56..ce66f32 100644
--- a/data/etc/privapp-permissions-platform.xml
+++ b/data/etc/privapp-permissions-platform.xml
@@ -277,6 +277,8 @@
         <permission name="android.permission.MOVE_PACKAGE"/>
         <permission name="android.permission.OBSERVE_APP_USAGE"/>
         <permission name="android.permission.PACKAGE_USAGE_STATS" />
+        <!-- Needed for test only -->
+        <permission name="android.permission.PACKET_KEEPALIVE_OFFLOAD" />
         <permission name="android.permission.POWER_SAVER" />
         <permission name="android.permission.READ_FRAME_BUFFER"/>
         <permission name="android.permission.READ_LOWPAN_CREDENTIAL"/>