qcom/audio/hal: Fix the device switch delay issue during voice call

- Device switch from earpiece to speaker during voice call takes
  around 3.5sec which is not acceptable
- Disabling the voice call mixer path consumes 3.5 sec
- Fixed by making sure that device path is deactivated on MDM through
  CSD client before disabling voice call mixer path on APQ.
- Also remove incorrect calls to dlerror() and make the dlsym-error messages
  more consistent.

Change-Id: Ib23c0a3c0341f41904ca06524bf9d2f4214ad92e
Signed-off-by: Iliyan Malchev <malchev@google.com>