lshal: exhaust pipe before closing.

If there is a pending close request on the pipe,
but there's still data in the pipe, exhaust it.

Test: com.google.android.power.pts.PowerTest#power2RockBottomCheckTest
Bug: 200623090

Change-Id: Iaaa4ba0c3af480671d7d63f9b2dbf682277a3430
1 file changed