Fix memory leaks in Bluez specific device and SDP discovery classes.

[ChangeLog][QtBluetooth][Platform Specific Changes] Memory leaks fixed
in Bluez device and service discovery implementations.

Change-Id: Ibc7c883d42d81a97310ff44ba40ffa94c71f611f
Reviewed-by: Fabian Bumberger <fbumberger@rim.com>
Reviewed-by: Aaron McCarthy <mccarthy.aaron@gmail.com>
Reviewed-by: Alex Blasche <alexander.blasche@digia.com>