Settings : Don't disable persisting for MultiSelectListPreference

There is an aosp bug where MultiSelectListPreference stores a custom state type,
but doesn't override onRestoreState and causes an exception to be thrown when inside
activities that don't override orientation change.

This patch resolves this issue by persisting the preference change, which bypasses that route.
No functional impact since we override the values from the settings provider onresume anyway.

Repro :

    - Launch dialer
    - Launch Settings
    - Launch blacklist
    - Launch settings
    - Rotate phone
    - Realize you need this patch :)

Change-Id: Ie51119190fa6c43db612223bdb60c00fe607b9bf

Author: Danesh

res/xml/blacklist_prefs.xml

@@ -27,16 +27,14 @@
         android:title="@string/blacklist_private_numbers_title"
         android:dialogTitle="@string/blacklist_private_numbers_title"
         android:entries="@array/blacklist_policy_private_entries"
-        android:entryValues="@array/blacklist_policy_private_values"
-        android:persistent="false" />
+        android:entryValues="@array/blacklist_policy_private_values" />
 
     <MultiSelectListPreference
         android:key="button_blacklist_unknown_numbers"
         android:title="@string/blacklist_unknown_numbers_title"
         android:dialogTitle="@string/blacklist_unknown_numbers_title"
         android:entries="@array/blacklist_policy_unknown_entries"
-        android:entryValues="@array/blacklist_policy_unknown_values"
-        android:persistent="false" />
+        android:entryValues="@array/blacklist_policy_unknown_values" />
 
     <com.android.settings.cyanogenmod.SystemSettingCheckBoxPreference
         android:key="phone_blacklist_regex_enabled"