Use correct sbcl package variable.

* modules/jenkins/manifests/slave.pp: Use
$::jenkins::params::sbcl_package instead of $::jenkins::params::sbcl so
that puppet has a valid package to install.

Change-Id: I47526b704dd8bdf1ecd90113cd363ec5a22f4a00
Reviewed-on: https://review.openstack.org/34281
Reviewed-by: Jeremy Stanley <fungi@yuggoth.org>
Approved: Monty Taylor <mordred@inaugust.com>
Reviewed-by: Monty Taylor <mordred@inaugust.com>
Tested-by: Jenkins