Bluetooth: hci_conn: Fix not setting timeout for BIG Create Sync

BIG Create Sync requires the command to just generates a status so this
makes use of __hci_cmd_sync_status_sk to wait for
HCI_EVT_LE_BIG_SYNC_ESTABLISHED, also because of this chance it is not
longer necessary to use a custom method to serialize the process of
creating the BIG sync since the cmd_work_sync itself ensures only one
command would be pending which now awaits for
HCI_EVT_LE_BIG_SYNC_ESTABLISHED before proceeding to next connection.

Fixes: 42ecf194 ("Bluetooth: ISO: Do not emit LE BIG Create Sync if previous is pending")
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>