Merge branch 'bugfix/vhci_callback' into 'release/v2.0'

component/bt: let "vhci_notify_host_send_available" be called in task context

Previously the callback function "vhci_notify_host_send_available" can be called in both interrupt context or BT controller task context, which is one of the cause that Bluedroid tasks cannot work on dual CPUs. 

See merge request !603

components/bt/lib

@@ -1 +1 @@
-Subproject commit 9a4bb1d5287572664f170f9df4dbfd71babdfc68
+Subproject commit 5164b8cb0c1db58f2957b4cf885361719f5fcf8c