Bluetooth: Add clarifying comment when setting local OOB flag

It might be a bit counterintuitive to set a 'local' flag based on remote
data. This patch adds a clarifying comment to the pairing req/rsp
handlers when setting the LOCAL_OOB flag based on the PDU received from
the remote side.

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