jjb: xci: Fix permissions in workspace before removing it

jjb: xci: Fix permissions in workspace before removing it

From time to time we end up in the unfortunate situation where
the jenkins job breaks for random reasons and the logs are left
with 'root' permissions. On the next run, the job fails again but
this time it's because Jenkins does not have enough permissions
to delete them. We workaround this by fixing up the permissions
before removing the workspace.

Change-Id: I2fda20ded527bac73605ffa5818a2c44bf6c9026
Signed-off-by: Markos Chandras <mchandras@suse.de>