Improved data fail cause debug message

Test: Manual
Fix: 228611718
Change-Id: Ic3a5a64a4e57ed49dd4445ff31018b78e833f73f

telephony/java/android/telephony/DataFailCause.java

@@ -1661,8 +1661,8 @@ public final class DataFailCause {
 
     /** @hide */
     public static String toString(@DataFailureCause int dataFailCause) {
-        int cause = getFailCause(dataFailCause);
-        return (cause == UNKNOWN) ? "UNKNOWN(" + dataFailCause + ")" : sFailCauseMap.get(cause);
+        return sFailCauseMap.getOrDefault(dataFailCause, "UNKNOWN") + "(0x"
+                + Integer.toHexString(dataFailCause) + ")";
     }
 
     /** @hide */

telephony/java/android/telephony/data/DataCallResponse.java

@@ -428,7 +428,7 @@ public final class DataCallResponse implements Parcelable {
     public String toString() {
         StringBuffer sb = new StringBuffer();
         sb.append("DataCallResponse: {")
-           .append(" cause=").append(mCause)
+           .append(" cause=").append(DataFailCause.toString(mCause))
            .append(" retry=").append(mSuggestedRetryTime)
            .append(" cid=").append(mId)
            .append(" linkStatus=").append(mLinkStatus)