timer vty: also print the default value in cmd doc

Rationale: allows seeing all timer defaults at once by doing

  OsmoBSC(config-net)# timer ?

Before, defaults are visible only by doing on each timer:

  OsmoBSC(config-net)# timer t1234 <tab>

Change-Id: I8259234e5c62e058dde56d531071440bbab11462
1 file changed