jjb: lttng-modules: fix RT jobs failure

Add the 'distroversion' parameter to lttng-modules_PARAM_build jobs
triggered in 'master-rt.groovy'. This fixes the following error:

  Run condition [Regular expression match] enabling prebuild for step [Execute shell]
  Exception caught evaluating condition: [org.jenkinsci.plugins.tokenmacro.MacroEvaluationException: Error processing tokens], action = [Fail the build]

Change-Id: I9f4eb6735e53e9ad7ea83d69b70a4ccf53843463
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>