Use audio_mode_t consistently

It was int or uint32_t.
Also make getMode() const.

Change-Id: Ibe45aadbf413b9158e4dd17f2b3bcc6355288d37
diff --git a/media/libmedia/IAudioPolicyService.cpp b/media/libmedia/IAudioPolicyService.cpp
index 50b4855..3a54347 100644
--- a/media/libmedia/IAudioPolicyService.cpp
+++ b/media/libmedia/IAudioPolicyService.cpp
@@ -91,7 +91,7 @@
         return static_cast <audio_policy_dev_state_t>(reply.readInt32());
     }
 
-    virtual status_t setPhoneState(int state)
+    virtual status_t setPhoneState(audio_mode_t state)
     {
         Parcel data, reply;
         data.writeInterfaceToken(IAudioPolicyService::getInterfaceDescriptor());
@@ -394,7 +394,7 @@
 
         case SET_PHONE_STATE: {
             CHECK_INTERFACE(IAudioPolicyService, data, reply);
-            reply->writeInt32(static_cast <uint32_t>(setPhoneState(data.readInt32())));
+            reply->writeInt32(static_cast <uint32_t>(setPhoneState((audio_mode_t) data.readInt32())));
             return NO_ERROR;
         } break;