aaudio: call validate() from readFromParcel()

This is to ensure that validate() is always called
in the future.

Bug: 74558178
Test: run AAudio CTS
Test: on Marlin, adb shell write_sine_callback -pl
Change-Id: I661f3c4e690be2268ca61b80a98bbdf9a7368c1b
diff --git a/media/libaaudio/src/binding/SharedRegionParcelable.h b/media/libaaudio/src/binding/SharedRegionParcelable.h
index f6babfd..0cd8c04 100644
--- a/media/libaaudio/src/binding/SharedRegionParcelable.h
+++ b/media/libaaudio/src/binding/SharedRegionParcelable.h
@@ -47,14 +47,15 @@
 
     bool isFileDescriptorSafe(SharedMemoryParcelable *memoryParcels);
 
-    aaudio_result_t validate();
-
     void dump();
 
 protected:
     int32_t mSharedMemoryIndex = -1;
     int32_t mOffsetInBytes     = 0;
     int32_t mSizeInBytes       = 0;
+
+private:
+    aaudio_result_t validate() const;
 };
 
 } /* namespace aaudio */