Add summary for white balance feature

Create a string id for summary.
This string should be empty string for AOSP.

Test: visual
Bug: 134790233
Change-Id: I06b5d0b35ac08565d3496f8559f5bd85cd56c6b8
diff --git a/res/values/strings.xml b/res/values/strings.xml
index 303e646..37f2f1d 100644
--- a/res/values/strings.xml
+++ b/res/values/strings.xml
@@ -2829,6 +2829,8 @@
 
     <!-- Display settings screen, display white balance settings title [CHAR LIMIT=30] -->
     <string name="display_white_balance_title">Display white balance</string>
+    <!-- Display settings screen, display white balance settings summary [CHAR LIMIT=NONE] -->
+    <string name="display_white_balance_summary"></string>
     <!-- Display settings screen, setting option name to enable adaptive sleep [CHAR LIMIT=30] -->
     <string name="adaptive_sleep_title">Screen attention</string>
     <!-- Setting option summary when adaptive sleep is on [CHAR LIMIT=NONE] -->
diff --git a/res/xml/display_settings.xml b/res/xml/display_settings.xml
index ad06e95..54b43dc 100644
--- a/res/xml/display_settings.xml
+++ b/res/xml/display_settings.xml
@@ -93,6 +93,7 @@
     <SwitchPreference
         android:key="display_white_balance"
         android:title="@string/display_white_balance_title"
+        android:summary="@string/display_white_balance_summary"
         settings:controller="com.android.settings.display.DisplayWhiteBalancePreferenceController" />
 
     <Preference