Bluetooth: hci_event: Fix not marking Broadcast Sink BIS as connected

Upon receiving HCI_EVT_LE_BIG_SYNC_ESTABLISHED with status 0x00
(success) the corresponding BIS hci_conn state shall be set to
BT_CONNECTED otherwise they will be left with BT_OPEN which is invalid
at that point, also create the debugfs and sysfs entries following the
same logic as the likes of Broadcast Source BIS and CIS connections.

Fixes: f777d882 ("Bluetooth: ISO: Notify user space about failed bis connections")
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>