Bluetooth: Rename connectable_addr member in struct bt_le_oob

Depending on advertising options this can be non-connectable address.
NFC pairing application document also allows broadcaster/observer
roles.

Change-Id: I9b104ac8fb9752a083a7a31fc20598c66f23f608
Signed-off-by: Szymon Janc <ext.szymon.janc@tieto.com>