aaudio: prevent retrograde motion in Legacy timestamps

Use MonotonicCounter for timestamp position.

Bug: 63918065
Test: write_sine_callback.cpp and test_timestamps.cpp
Change-Id: Iea58384e2d96adcfad586e8c522024baaecccb8c
diff --git a/media/libaaudio/src/utility/MonotonicCounter.h b/media/libaaudio/src/utility/MonotonicCounter.h
index 81d7f89..13c92a2 100644
--- a/media/libaaudio/src/utility/MonotonicCounter.h
+++ b/media/libaaudio/src/utility/MonotonicCounter.h
@@ -41,6 +41,13 @@
     }
 
     /**
+     * set the current value of the counter
+     */
+    void set(int64_t counter) {
+        mCounter64 = counter;
+    }
+
+    /**
      * Advance the counter if delta is positive.
      * @return current value of the counter
      */