Bluetooth: hci_sync: Convert MGMT_OP_READ_LOCAL_OOB_EXT_DATA

Uses existing *_sync functions

mgmt-test paths:
Read Local OOB Ext Data - Invalid index
Read Local OOB Ext Data - Legacy pairing
Read Local OOB Ext Data - Success SSP
Read Local OOB Ext Data - Success SC

Signed-off-by: Brian Gix <brian.gix@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>