Bluetooth: Add the definition and stcuture for Sync Train Complete

The Synchronization Train Complete event indicates that the Start
Synchronization Train command has completed.

The Core Spec Addendum 4 adds this command in part B Connectionless
Slave Broadcast.

Bluetooth Core Specification Addendum 4 - Page 103

"7.7.67 Synchronization Train Complete Event [New Section]
...

Event Parameters:

Status 0x00       Start Synchronization Train command completed
                  successfully.
       0x01-0xFF  Start Synchronization Train command failed.
                  See Part D, Error Codes, for error codes and
                  descriptions."

Signed-off-by: Dohyun Pyun <dh79.pyun@samsung.com>
Signed-off-by: C S Bhargava <cs.bhargava@samsung.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>