Add new APIs to set or get preferred built-in device

Add new APIs to set or get preferred built-in device

These new APIs are to set or get a specific built-in device when
the system has multiple devices of the same built-in device type.

When there's only one device for a built-in device type in the system,
nothing will happen even if these functions succeed in operation.

 - sound_manager_set_preferred_device
 - sound_manager_get_preferred_device

[Version] 0.5.32
[Issue Type] New feature

Change-Id: I7a709462031238de4127d9e6a5087577245f1627
Signed-off-by: Sangchul Lee <sc11.lee@samsung.com>