Bluetooth: hci_sync: fix hci_conn_del() use in hci_le_create_conn_sync

Bluetooth: hci_sync: fix hci_conn_del() use in hci_le_create_conn_sync

hci_conn_del() caller must hold hdev->lock, check the conn was not
concurrently deleted, and usually inform socket the conn is going to be
deleted.

Use hci_abort_conn_sync() instead of calling hci_conn_del() without
locks etc.

Fixes: 8e8b92ee60de5 ("Bluetooth: hci_sync: Add hci_le_create_conn_sync")
Signed-off-by: Pauli Virtanen <pav@iki.fi>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>