Migrate 'csp_enabled' to CarrierConfigManager.

This variable controls whether SIM cards are allowed to disable manual
carrier selection, so it makes more sense for it to be managed as
carrier config.

Currently the variable is only used in *DEVICE* overlays for specific
networks, but we are dropping the device-overlay so that this simply
applies to those same networks.

Change-Id: I9ab91f79b55a88e725d789a942265da1afc3b979
diff --git a/src/com/android/phone/GsmUmtsOptions.java b/src/com/android/phone/GsmUmtsOptions.java
index df5f2cd..d12bac9 100644
--- a/src/com/android/phone/GsmUmtsOptions.java
+++ b/src/com/android/phone/GsmUmtsOptions.java
@@ -85,7 +85,7 @@
                         .findPreference(BUTTON_OPERATOR_SELECTION_EXPAND_KEY));
             }
 
-            if (res.getBoolean(R.bool.csp_enabled)) {
+            if (carrierConfig.getBoolean(CarrierConfigManager.KEY_CSP_ENABLED_BOOL)) {
                 if (PhoneFactory.getDefaultPhone().isCspPlmnEnabled()) {
                     log("[CSP] Enabling Operator Selection menu.");
                     mButtonOperatorSelectionExpand.setEnabled(true);