Add legacy HAL get audio device port method

Audio device factory only exposes a single HIDL version. Devices
using previous versions of the HIDL HAL will not be able to use BT audio
HAL since the get device port will not be available.

Bug: 305301155
Test: m -j, test manual
Change-Id: I9cd92218a0d32fd22c44a9cc4f0e86adb02c92fe