Fix reference leak on TvInputManagerService

Fix reference leak when TV input changed.

Test: 1. Modify to call android.os.Debug.dumpReferenceTables() in
TvInputManagerService#onServiceConnected
2. Build and run
3. Repeat to launch and finish TV player application with logcat output
4. Confirm Global Reference Table information on logcat whether
reference increase

Change-Id: I9b9896115088d8b179a9cf29ddca88e8a8fa529a