aaudio: use unique_ptr in FixedBlockAdapter

Code cleanup.

Test: atest CtsNativeMediaAAudioTestCases
Change-Id: I980862379ade9b6cc62f1743c916208e3911a00a
diff --git a/media/libaaudio/src/utility/FixedBlockReader.cpp b/media/libaaudio/src/utility/FixedBlockReader.cpp
index 21ea70e..7931fa0 100644
--- a/media/libaaudio/src/utility/FixedBlockReader.cpp
+++ b/media/libaaudio/src/utility/FixedBlockReader.cpp
@@ -39,7 +39,7 @@
     if (bytesToRead > dataAvailable) {
         bytesToRead = dataAvailable;
     }
-    memcpy(buffer, mStorage + mPosition, bytesToRead);
+    memcpy(buffer, &mStorage[mPosition], bytesToRead);
     mPosition += bytesToRead;
     return bytesToRead;
 }
@@ -60,7 +60,7 @@
             bytesLeft -= mSize;
         } else {
             // Just need a partial block so we have to use storage.
-            result = mFixedBlockProcessor.onProcessFixedBlock(mStorage, mSize);
+            result = mFixedBlockProcessor.onProcessFixedBlock(mStorage.get(), mSize);
             mPosition = 0;
         }
     }