More lowenergyscanner example fixes.

This fixes a UI display bug and a hanging UI when the service discovery
aborts with an error.

Change-Id: Ic84d7b885d777360c8f1396e3973623c1d2c550a
Reviewed-by: Timur Pocheptsov <Timur.Pocheptsov@digia.com>
Reviewed-by: Alex Blasche <alexander.blasche@theqtcompany.com>