samples: bluetooth: ibeacon: change to ADV_NONCONN_IND type

According to the Apple iBeacon spec chapter "2.1 Advertising Packet",
"beacons must use a non connectable undirected Advertising PDU,
ADV_NONCONN_IND". Refer to https://developer.apple.com/ibeacon/



Signed-off-by: Aaron Tsui <aaron.tsui@outlook.com>