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