hal: Correct the condition to open haptics stream.

- Correct the condition to open haptics stream to check for haptics
  device availability.
- Sometimes, stream out constructor and destructor won't be called, as
  hal client uses same session based on flags.
  In that case, haptics_device was not getting freed, so add free of
  haptics device to Standby as well.

Change-Id: I11d5bee300201a422f06b34a77e3805007de10d8