CRAS BT: use cras_bt_transport in bt_profile

Use cras_bt_transport to carry the necessary information
for cras_iodev creation in bt profile connection/disconnection.

BUG=chromium:232315
TEST=Unittest

Change-Id: Ic8ce2d41824dda5e36d17cf75724faa601256eaa
Reviewed-on: https://gerrit.chromium.org/gerrit/62811
Reviewed-by: Hsinyu Chao <hychao@chromium.org>
Tested-by: Hsinyu Chao <hychao@chromium.org>
Commit-Queue: Hsinyu Chao <hychao@chromium.org>
5 files changed