Bluetooth: Make mgmt_read_local_oob_data_reply_complete() return void

The return value of mgmt_read_local_oob_data_reply_complete() function
is not used and so just change it to return void.

Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>