Add SettingsMultiSelectListPreference style

There is no OK and CANCEL button when changing APN Bearer.
To fix this issue, OK and CANCEL button should be added to
SettingsMultiSelectListPreference style.

Fixes: 66928311
Test: manual - Add a new APN and tap Bearer

Change-Id: I2b5719a7c1fdb721b15308e0eef7db3e6398e097
diff --git a/res/values/styles_preference.xml b/res/values/styles_preference.xml
index 5fe1ef4..6b632ca 100644
--- a/res/values/styles_preference.xml
+++ b/res/values/styles_preference.xml
@@ -40,4 +40,9 @@
         <item name="android:layout">@layout/two_state_button</item>
     </style>
 
+    <style name="SettingsMultiSelectListPreference" parent="Preference.SettingsBase">
+        <item name="android:positiveButtonText">@android:string/ok</item>
+        <item name="android:negativeButtonText">@android:string/cancel</item>
+    </style>
+
 </resources>
\ No newline at end of file
diff --git a/res/xml/apn_editor.xml b/res/xml/apn_editor.xml
index b1e332b..742a436 100644
--- a/res/xml/apn_editor.xml
+++ b/res/xml/apn_editor.xml
@@ -157,6 +157,7 @@
         android:entries="@array/bearer_entries"
         android:entryValues="@array/bearer_values"
         android:persistent="false"
+        style="@style/SettingsMultiSelectListPreference"
         />
     <ListPreference
         android:title="@string/mvno_type"