alsa_sound: Restrict the number of opened input streams

 -For hangout VOIP call, since the sample rate is 48k,
  the input stream is opened as a normal recording use case
  and next when sound recorder is started it attempts to
  open the same pcm device which returns an EBUSY error.
 -Adding a check to not open the input stream for recording
  if already in use.

 CRs-Fixed: 532149

Change-Id: I3ce3208a42a406eb8d52ed38ba7b20f7c6618822