Do not fail while parsing speaker_drc_enabled entry in audio_policy.conf

Fixed parsing following section in /system/etc/audio_policy.conf

global_configuration {
  attached_output_devices AUDIO_DEVICE_OUT_EARPIECE|AUDIO_DEVICE_OUT_SPEAKER
  default_output_device AUDIO_DEVICE_OUT_SPEAKER
  attached_input_devices AUDIO_DEVICE_IN_BUILTIN_MIC|AUDIO_DEVICE_IN_BACK_MIC|AUDIO_DEVICE_IN_REMOTE_SUBMIX
  speaker_drc_enabled TRUE
}