audioflinger: Clear InputSource in RecordThread::clearInput

This is for consistency with 'clearOutput' which clears the sink.

The intention is to facilitate releasing of the HAL stream which
is one of possible NBAIO_Source implementations.

Bug: 298175108
Test: atest audiosystem_tests
Change-Id: I7d087836f1c57ff4872c355eac5d3ecad724b5a8
diff --git a/services/audioflinger/Threads.cpp b/services/audioflinger/Threads.cpp
index a6630a8..09583aa 100644
--- a/services/audioflinger/Threads.cpp
+++ b/services/audioflinger/Threads.cpp
@@ -9237,6 +9237,7 @@
     Mutex::Autolock _l(mLock);
     AudioStreamIn *input = mInput;
     mInput = NULL;
+    mInputSource.clear();
     return input;
 }