audio: Close the file descriptor in error scenarios

 -In the scenario where the USB headset and proxy device
  sample rate dont match, error was returned without
  closing the file descriptor .So, the next time USB
  headset is inserted , the /proc entries are not created
  which results in the USB headset playback not started
  as the capabilities cannot be read.
 - Closing the file descriptor in the error scenario fixes
  the issue.

Change-Id: Ie45327f04cc7fff6dbcbe1268a7f34793e89641b