Bluetooth: ISO: Send BIG Create Sync via hci_sync

Bluetooth: ISO: Send BIG Create Sync via hci_sync

Before issuing the LE BIG Create Sync command, an available BIG handle
is chosen by iterating through the conn_hash list and finding the first
unused value.

If a BIG is terminated, the associated hcons are removed from the list
and the LE BIG Terminate Sync command is sent via hci_sync queue.
However, a new LE BIG Create sync command might be issued via
hci_send_cmd, before the previous BIG sync was terminated. This
can cause the same BIG handle to be reused and the LE BIG Create Sync
to fail with Command Disallowed.

< HCI Command: LE Broadcast Isochronous Group Create Sync (0x08|0x006b)
        BIG Handle: 0x00
        BIG Sync Handle: 0x0002
        Encryption: Unencrypted (0x00)
        Broadcast Code[16]: 00000000000000000000000000000000
        Maximum Number Subevents: 0x00
        Timeout: 20000 ms (0x07d0)
        Number of BIS: 1
        BIS ID: 0x01
> HCI Event: Command Status (0x0f) plen 4
      LE Broadcast Isochronous Group Create Sync (0x08|0x006b) ncmd 1
        Status: Command Disallowed (0x0c)
< HCI Command: LE Broadcast Isochronous Group Terminate Sync (0x08|0x006c)
        BIG Handle: 0x00

This commit fixes the ordering of the LE BIG Create Sync/LE BIG Terminate
Sync commands, to make sure that either the previous BIG sync is
terminated before reusing the handle, or that a new handle is chosen
for a new sync.

Fixes: eca0ae4aea66 ("Bluetooth: Add initial implementation of BIS connections")
Signed-off-by: Iulia Tanasescu <iulia.tanasescu@nxp.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>