Fixed a UI bug that would disable Cellular Networks screen.

Bug: 17152922
Change-Id: I0e565db6af1f64298bbedb64a4dc47e74f624979
diff --git a/src/com/android/phone/MobileNetworkSettings.java b/src/com/android/phone/MobileNetworkSettings.java
index 05c00fa..1806558 100644
--- a/src/com/android/phone/MobileNetworkSettings.java
+++ b/src/com/android/phone/MobileNetworkSettings.java
@@ -124,6 +124,7 @@
         // Assuming that onClick gets called first
         if (!mOkClicked) {
             mButtonDataRoam.setChecked(false);
+            getPreferenceScreen().setEnabled(true);
         }
     }