Don't cache the QBluetoothSocket::localName() & peerName()

This affects Bluez only. The other platforms don't use this feature.
The problem was triggered when connecting, disconnecting and connecting
again to another device. localName() might change due to a different
local Bluetooth adapter being used and peerName() is different anyway
in such cases.

Change-Id: I8983a355832cf4f4d9a654971c54f5624be288e6
Reviewed-by: Fabian Bumberger <fbumberger@rim.com>
Reviewed-by: Alex Blasche <alexander.blasche@digia.com>