Small improvements in audio_policy dump

 1. Introduce a formatting helper for audio_mode_t, use it.
 2. Get rid of mSize in TypeConverter.
 3. Convert to a string unknown enum values.

Change-Id: I8fc222225c2dd48dea715bb3fe4ecb3f1eaecc46
diff --git a/services/audiopolicy/managerdefault/AudioPolicyManager.cpp b/services/audiopolicy/managerdefault/AudioPolicyManager.cpp
index a19a4be..444e48a 100644
--- a/services/audiopolicy/managerdefault/AudioPolicyManager.cpp
+++ b/services/audiopolicy/managerdefault/AudioPolicyManager.cpp
@@ -2258,7 +2258,9 @@
     snprintf(buffer, SIZE, " Primary Output: %d\n",
              hasPrimaryOutput() ? mPrimaryOutput->mIoHandle : AUDIO_IO_HANDLE_NONE);
     result.append(buffer);
-    snprintf(buffer, SIZE, " Phone state: %d\n", mEngine->getPhoneState());
+    std::string stateLiteral;
+    AudioModeConverter::toString(mEngine->getPhoneState(), stateLiteral);
+    snprintf(buffer, SIZE, " Phone state: %s\n", stateLiteral.c_str());
     result.append(buffer);
     snprintf(buffer, SIZE, " Force use for communications %d\n",
              mEngine->getForceUse(AUDIO_POLICY_FORCE_FOR_COMMUNICATION));