Handle null pointer exception

Handle null pointer exception, just in case calling entitity doesn't
check.

Change-Id: I1b4809476cc689ad3dfd426e123a64e9a0336c87
diff --git a/packages/SettingsProvider/src/com/android/providers/settings/SettingsProvider.java b/packages/SettingsProvider/src/com/android/providers/settings/SettingsProvider.java
index 1896bbb..57d495f 100644
--- a/packages/SettingsProvider/src/com/android/providers/settings/SettingsProvider.java
+++ b/packages/SettingsProvider/src/com/android/providers/settings/SettingsProvider.java
@@ -1010,7 +1010,7 @@
                 break;
 
             default:
-                if (setting.startsWith(Settings.Global.DATA_ROAMING)) {
+                if (setting != null && setting.startsWith(Settings.Global.DATA_ROAMING)) {
                     if ("0".equals(value)) return false;
                     restriction = UserManager.DISALLOW_DATA_ROAMING;
                     break;