Rename key usage to start with "KEY"

CarrierConfigTest validates carrier_config xmls by comparing them to
static fields starting with "KEY_". This commit fixes the key's name in
TelephonyConnection.

Change-Id: Ia56cfd52328896368b9e0ab1fc129f55cc8f5856
Test: runtest carrierconfig-unit
diff --git a/src/com/android/services/telephony/TelephonyConnection.java b/src/com/android/services/telephony/TelephonyConnection.java
index 30aca49..078b025 100644
--- a/src/com/android/services/telephony/TelephonyConnection.java
+++ b/src/com/android/services/telephony/TelephonyConnection.java
@@ -885,7 +885,7 @@
         String[] filteredCnapNames = null;
         if (carrierConfig != null) {
             filteredCnapNames = carrierConfig.getStringArray(
-                    CarrierConfigManager.FILTERED_CNAP_NAMES_STRING_ARRAY);
+                    CarrierConfigManager.KEY_FILTERED_CNAP_NAMES_STRING_ARRAY);
         }
         if (filteredCnapNames != null) {
             long cnapNameMatches = Arrays.asList(filteredCnapNames)