bt: update bt a2dp offload capabilities

* set BtA2dpOffloadCap value to sbc-aac-aptx-aptxhd-ldac-opus
  in bt_vendor_overlay.conf to suppot OPUS offloading.

Bug: 243958304
Test: manully
Change-Id: I0482a86584ad0ae36daff810a1c853e8edffd375
1 file changed