Bluetooth: Add the definition for Start Synchronization Train

The Start_Synchronization_Train command controls the Synchronization
Train functionality in the BR/EDR Controller.

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

Bluetooth Core Specification Addendum 4 - Page 86

"7.1.51 Start Synchronization Train Command [New Section]
...
If connectionless slave broadcast mode is not enabled, the Command
Disallowed (0x0C) error code shall be returned. After receiving this
command and returning a Command Status event, the Baseband starts
attempting to send synchronization train packets containing information
related to the enabled Connectionless Slave Broadcast packet timing.

Note: The AFH_Channel_Map used in the synchronization train packets is
configured by the Set_AFH_Channel_Classification command and the local
channel classification in the BR/EDR Controller.

The synchronization train packets will be sent using the parameters
specified by the latest Write_Synchronization_Train_Parameters command.
The Synchronization Train will continue until synchronization_trainTO
slots (as specified in the last Write_Synchronization_Train command)
have passed or until the Host disables the Connectionless Slave Broadcast
logical transport."
Signed-off-by: NDohyun Pyun <dh79.pyun@samsung.com>
Signed-off-by: NC S Bhargava <cs.bhargava@samsung.com>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

include/net/bluetooth/hci.h

@@ -644,6 +644,8 @@ struct hci_rp_set_csb {
 	__le16	interval;
 } __packed;
 
+#define HCI_OP_START_SYNC_TRAIN		0x0443
+
 #define HCI_OP_SNIFF_MODE		0x0803
 struct hci_cp_sniff_mode {
 	__le16   handle;