BTM_SCO HCI path handling

Only handle CVSD case for now (just PCM).
Read data from audio service and send when we receive a packet from the
remote for now.

Tag: #refactor
Test: cert/run
Bug: 195344796
Change-Id: I647ba0392a19ba50ca4dd659aa02ade240a43afb
diff --git a/system/stack/BUILD.gn b/system/stack/BUILD.gn
index 0975629..a0c1b6b 100644
--- a/system/stack/BUILD.gn
+++ b/system/stack/BUILD.gn
@@ -120,6 +120,7 @@
     "btm/btm_main.cc",
     "btm/btm_scn.cc",
     "btm/btm_sco.cc",
+    "btm/btm_sco_hci.cc",
     "btm/btm_sec.cc",
     "btu/btu_hcif.cc",
     "btu/btu_task.cc",