aaudio: cleanup FIFO

Remove unused methods and fields.
Better code format and alignment.
Use unique_ptr for mFifo.
Remove getFifoController() method that exposed pointer.
Updates tests and calling code as needed.

Test: test_atomic_fifo.cpp
Change-Id: I1ea66beaadeb74083307835858b757e4753affda
diff --git a/media/libaaudio/src/fifo/FifoController.h b/media/libaaudio/src/fifo/FifoController.h
index 79d98a1..057a94e 100644
--- a/media/libaaudio/src/fifo/FifoController.h
+++ b/media/libaaudio/src/fifo/FifoController.h
@@ -30,7 +30,7 @@
 class FifoController : public FifoControllerBase
 {
 public:
-    FifoController(fifo_counter_t bufferSize, fifo_counter_t threshold)
+    FifoController(fifo_frames_t bufferSize, fifo_frames_t threshold)
     : FifoControllerBase(bufferSize, threshold)
     , mReadCounter(0)
     , mWriteCounter(0)