Simplify range check for audio_mode_t (continued)

Missed one place in earlier CL of same name

Change-Id: I0dd25364d0b8d5d731c02d352f139a0c8d4df1a8

media/libmedia/AudioSystem.cpp

@@ -538,6 +538,7 @@ audio_policy_dev_state_t AudioSystem::getDeviceConnectionState(audio_devices_t d
 
 status_t AudioSystem::setPhoneState(audio_mode_t state)
 {
+    if (uint32_t(state) >= AUDIO_MODE_CNT) return BAD_VALUE;
     const sp<IAudioPolicyService>& aps = AudioSystem::get_audio_policy_service();
     if (aps == 0) return PERMISSION_DENIED;