Use audio_mode_t consistently

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

Change-Id: Ibe45aadbf413b9158e4dd17f2b3bcc6355288d37
diff --git a/include/media/AudioSystem.h b/include/media/AudioSystem.h
index 6a15f6e..9369078 100644
--- a/include/media/AudioSystem.h
+++ b/include/media/AudioSystem.h
@@ -62,8 +62,8 @@
     static status_t setStreamMute(int stream, bool mute);
     static status_t getStreamMute(int stream, bool* mute);
 
-    // set audio mode in audio hardware (see audio_mode_t)
-    static status_t setMode(int mode);
+    // set audio mode in audio hardware
+    static status_t setMode(audio_mode_t mode);
 
     // returns true in *state if tracks are active on the specified stream or has been active
     // in the past inPastMs milliseconds
@@ -142,7 +142,7 @@
     //
     static status_t setDeviceConnectionState(audio_devices_t device, audio_policy_dev_state_t state, const char *device_address);
     static audio_policy_dev_state_t getDeviceConnectionState(audio_devices_t device, const char *device_address);
-    static status_t setPhoneState(int state);
+    static status_t setPhoneState(audio_mode_t state);
     static status_t setRingerMode(uint32_t mode, uint32_t mask);
     static status_t setForceUse(audio_policy_force_use_t usage, audio_policy_forced_cfg_t config);
     static audio_policy_forced_cfg_t getForceUse(audio_policy_force_use_t usage);