Fix crash when deleting certificates

The certificate delation is already handled by
BlackBerryConfiguration::syncCertificates() method.

Change-Id: Ia2f340fe4ad6d5cadbaf391430cd3ded656bbd46
Reviewed-by: Mehdi Fekari <mfekari@rim.com>
Reviewed-by: Tobias Nätterlund <tobias.naetterlund@kdab.com>
Reviewed-by: Nicolas Arnaud-Cormos <nicolas@kdab.com>