Move call of PulseExpansionHandler.setUp to startable

Previously, NPVC was passing NSSLC to it during intialization, but
a startable makes this slightly cleaner. The best way to do this would
be to inject it directly, but that would cause Dagger issues in the TV
variant.

Test: manually verified pulsing still works
Fixes: 348017860
Flag: EXEMPT no functional changes
Change-Id: I15127b36a8b24f953e4688b3d1f383f787e54109