Fix support for AIDL client calling startProgramListUpdates(null).

ag/7063548 inadvertently changed the behavior of calling
startProgramListUpdates(null) to be equivalent to
stopProgramListUpdates(). This change restores the original behavior
of the AIDL client receiving all program list updates.

Bug: 121305828
Test: atest com.android.server.broadcastradio.hal2.StartProgramListUpdatesFanoutTest
Change-Id: I60d21816d314b682585d6bcff6732675eef55a9b
2 files changed