IMS:change enhanced 4g setting to store in setting db.

Change-Id: I2ec37478e2bef5b15b157e490f75d5dda5f97117
diff --git a/core/java/android/provider/Settings.java b/core/java/android/provider/Settings.java
index e7ac6f6..75c435e 100644
--- a/core/java/android/provider/Settings.java
+++ b/core/java/android/provider/Settings.java
@@ -6588,6 +6588,14 @@
         public static final String REQUIRE_PASSWORD_TO_DECRYPT = "require_password_to_decrypt";
 
         /**
+         * Whether the Volte/VT is enabled
+         * <p>
+         * Type: int (0 for false, 1 for true)
+         * @hide
+         */
+        public static final String VOLTE_VT_ENABLED = "volte_vt_enabled";
+
+        /**
          * Settings to backup. This is here so that it's in the same place as the settings
          * keys and easy to update.
          *