audio: Fixed input device check

- in_device is set to AUDIO_DEVICE_IN_BACK_MIC which
  includes AUDIO_DEVICE_BIT_IN mask. Any comparison
  of in_device with input devices always results in true
  as all the input devices include AUDIO_DEVICE_BIT_IN

- Removed AUDIO_DEVICE_BIT_IN from in_device to avoid
  wrong comparisons
CRs-Fixed: 724951

Change-Id: Ib816ad70c6793b29f79f4e36d42677739a0021c5