Bluetooth: Remove unneeded HCI_CONN_REMOTE_OOB connection flag

The HCI_CONN_REMOTE_OOB connection flag is used to indicate if the
pairing initiator has provided out-of-band data. However since that
value is no longer used in any decision making, just remove it.

It is actually unclear what purpose the OOB data present field from
the HCI IO Capability Response event serves in the first place. If
either side provided out-of-band data, then that data will be used
for pairing.

Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>