Fix ssh root certificates path for Blackberry playbook OS.

This was removed by commit 4c8d8a72ec65f409394075ef50401265e495c1dd
But without it Playbook OS 2.1.0.1753 could not access ssh properly.

Change-Id: I18e136eaede2a5dffeb10b5fe31023b9aef709cb
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Peter Hartmann <phartmann@blackberry.com>