Add get_auth_token permission to the permission module.

This CL introduces the new permission added to sepolicy in
(aosp/1517237), into keystore2 permission module.

Bug: 159475305, 159475191
Test: atest keystore2_test
Change-Id: Ie818f96e0a13b0c43246165a1eefc5c0bfc51637
diff --git a/keystore2/src/permission.rs b/keystore2/src/permission.rs
index 576ac3f..93e9ba1 100644
--- a/keystore2/src/permission.rs
+++ b/keystore2/src/permission.rs
@@ -308,6 +308,8 @@
         ChangePassword = 0x100,    selinux name: change_password;
         /// Checked when a UID is cleared.
         ClearUID = 0x200,    selinux name: clear_uid;
+        /// Checked when Credstore calls IKeystoreAuthorization to obtain auth tokens.
+        GetAuthToken = 0x400,  selinux name: get_auth_token;
     }
 );