Bluetooth: hci_sync: Rework init stages

This moves the init stages to use the hci_sync infra and in addition
to that have the stages as function tables so it is easier to change
the command sequence.

Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>